From e4345134b099a5469de9ac13423bc1e64b3e1e84 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 15 Jun 2018 17:28:21 -0700
Subject: [PATCH 01/13] react-test-renderer injects itself into DevTools if
 present

---
 .../src/ReactTestHostConfig.js                |   9 +-
 .../src/ReactTestRenderer.js                  |  15 +++
 .../src/ReactTestRendererComponentTree.js     |  19 +++
 ...ofilerDevToolsIntegration-test.internal.js | 108 ++++++++++++++++++
 4 files changed, 149 insertions(+), 2 deletions(-)
 create mode 100644 packages/react-test-renderer/src/ReactTestRendererComponentTree.js
 create mode 100644 packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js

diff --git a/packages/react-test-renderer/src/ReactTestHostConfig.js b/packages/react-test-renderer/src/ReactTestHostConfig.js
index 1a1e74a1e27df..8215f2653f16b 100644
--- a/packages/react-test-renderer/src/ReactTestHostConfig.js
+++ b/packages/react-test-renderer/src/ReactTestHostConfig.js
@@ -7,6 +7,7 @@
  * @flow
  */
 
+import {precacheFiberNode} from './ReactTestRendererComponentTree';
 import * as TestRendererScheduling from './ReactTestRendererScheduling';
 
 export type Type = string;
@@ -117,13 +118,15 @@ export function createInstance(
   hostContext: Object,
   internalInstanceHandle: Object,
 ): Instance {
-  return {
+  const instance = {
     type,
     props,
     children: [],
     rootContainerInstance,
     tag: 'INSTANCE',
   };
+  precacheFiberNode(internalInstanceHandle, instance);
+  return instance;
 }
 
 export function appendInitialChild(
@@ -172,10 +175,12 @@ export function createTextInstance(
   hostContext: Object,
   internalInstanceHandle: Object,
 ): TextInstance {
-  return {
+  const textInstance = {
     text,
     tag: 'TEXT',
   };
+  precacheFiberNode(internalInstanceHandle, textInstance);
+  return textInstance;
 }
 
 export const isPrimaryRenderer = true;
diff --git a/packages/react-test-renderer/src/ReactTestRenderer.js b/packages/react-test-renderer/src/ReactTestRenderer.js
index 669e1e7abd5f8..993e272230711 100644
--- a/packages/react-test-renderer/src/ReactTestRenderer.js
+++ b/packages/react-test-renderer/src/ReactTestRenderer.js
@@ -29,9 +29,11 @@ import {
   Profiler,
 } from 'shared/ReactTypeOfWork';
 import invariant from 'shared/invariant';
+import ReactVersion from 'shared/ReactVersion';
 
 import * as ReactTestHostConfig from './ReactTestHostConfig';
 import * as TestRendererScheduling from './ReactTestRendererScheduling';
+import {findFiberByHostInstance} from './ReactTestRendererComponentTree';
 
 type TestRendererOptions = {
   createNodeMock: (element: React$Element<any>) => any,
@@ -279,6 +281,10 @@ class ReactTestInstance {
     return this._currentFiber().memoizedProps;
   }
 
+  get treeBaseTime(): number {
+    return this._currentFiber().treeBaseTime || 0;
+  }
+
   get parent(): ?ReactTestInstance {
     let parent = this._fiber.return;
     while (parent !== null) {
@@ -510,4 +516,13 @@ const ReactTestRendererFiber = {
   unstable_setNowImplementation: TestRendererScheduling.setNowImplementation,
 };
 
+// Enable ReactTestRenderer to be used to test DevTools integration.
+// TODO (bvaughn) Perhaps this injection should be hidden behind a feature flag?
+TestRenderer.injectIntoDevTools({
+  findFiberByHostInstance,
+  bundleType: __DEV__ ? 1 : 0,
+  version: ReactVersion,
+  rendererPackageName: 'react-test-renderer',
+});
+
 export default ReactTestRendererFiber;
diff --git a/packages/react-test-renderer/src/ReactTestRendererComponentTree.js b/packages/react-test-renderer/src/ReactTestRendererComponentTree.js
new file mode 100644
index 0000000000000..35604686f3909
--- /dev/null
+++ b/packages/react-test-renderer/src/ReactTestRendererComponentTree.js
@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const randomKey = Math.random()
+  .toString(36)
+  .slice(2);
+const internalInstanceKey = '__reactInternalInstance$' + randomKey;
+
+export function findFiberByHostInstance(node) {
+  return node[internalInstanceKey];
+}
+
+export function precacheFiberNode(hostInst, node) {
+  node[internalInstanceKey] = hostInst;
+}
diff --git a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
new file mode 100644
index 0000000000000..8da55c43e414b
--- /dev/null
+++ b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
@@ -0,0 +1,108 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+describe('ReactProfiler DevTools integrate', () => {
+  let React;
+  let ReactTestRenderer;
+  let AdvanceTime;
+  let advanceTimeBy;
+  let hook;
+  let mockNow;
+
+  const mockNowForTests = () => {
+    let currentTime = 0;
+
+    mockNow = jest.fn().mockImplementation(() => currentTime);
+
+    ReactTestRenderer.unstable_setNowImplementation(mockNow);
+    advanceTimeBy = amount => {
+      currentTime += amount;
+    };
+  };
+
+  beforeEach(() => {
+    global.__REACT_DEVTOOLS_GLOBAL_HOOK__ = hook = {
+      inject: () => {},
+      onCommitFiberRoot: jest.fn((rendererId, root) => {}),
+      onCommitFiberUnmount: () => {},
+      supportsFiber: true,
+    };
+
+    jest.resetModules();
+
+    React = require('react');
+    ReactTestRenderer = require('react-test-renderer');
+
+    mockNowForTests();
+
+    AdvanceTime = class extends React.Component {
+      static defaultProps = {
+        byAmount: 10,
+        shouldComponentUpdate: true,
+      };
+      shouldComponentUpdate(nextProps) {
+        return nextProps.shouldComponentUpdate;
+      }
+      render() {
+        // Simulate time passing when this component is rendered
+        advanceTimeBy(this.props.byAmount);
+        return this.props.children || null;
+      }
+    };
+  });
+
+  it('should automatically profile all fibers if the DevTools hook is detected', () => {
+    const App = ({multiplier}) => {
+      advanceTimeBy(2);
+      return (
+        <React.unstable_Profiler id="Profiler" onRender={onRender}>
+          <AdvanceTime byAmount={3 * multiplier} shouldComponentUpdate={true} />
+          <AdvanceTime
+            byAmount={7 * multiplier}
+            shouldComponentUpdate={false}
+          />
+        </React.unstable_Profiler>
+      );
+    };
+
+    const onRender = jest.fn(() => {});
+    const rendered = ReactTestRenderer.create(<App multiplier={1} />);
+
+    expect(hook.onCommitFiberRoot).toHaveBeenCalledTimes(1);
+
+    // Measure observable timing using the Profiler component.
+    // The time spent in App (above the Profiler) won't be included in the durations,
+    // But needs to be acocunted for in the offset times.
+    expect(onRender).toHaveBeenCalledTimes(1);
+    expect(onRender).toHaveBeenCalledWith('Profiler', 'mount', 10, 10, 2, 12);
+    onRender.mockClear();
+
+    // Measure unobservable timing required by the DevTools profiler.
+    // At this point, the base time should include both:
+    // The time 2ms in the App component itself, and
+    // The 10ms spend in the Profiler sub-tree beneath.
+    expect(rendered.root.findByType(App).treeBaseTime).toBe(12);
+
+    rendered.update(<App multiplier={2} />);
+
+    // Measure observable timing using the Profiler component.
+    // The time spent in App (above the Profiler) won't be included in the durations,
+    // But needs to be acocunted for in the offset times.
+    expect(onRender).toHaveBeenCalledTimes(1);
+    expect(onRender).toHaveBeenCalledWith('Profiler', 'update', 6, 13, 14, 20);
+
+    // Measure unobservable timing required by the DevTools profiler.
+    // At this point, the base time should include both:
+    // The initial 9ms for the components that do not re-render, and
+    // The updated 6ms for the component that does.
+    expect(rendered.root.findByType(App).treeBaseTime).toBe(15);
+  });
+});

From 6a01fc177256ccccf5b6ed4fcff7752d8e60c8c6 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 15 Jun 2018 17:28:53 -0700
Subject: [PATCH 02/13] Fibers are always opted into ProfileMode if DevTools is
 present

---
 packages/react-reconciler/src/ReactFiber.js             | 8 ++++++++
 packages/react-reconciler/src/ReactFiberDevToolsHook.js | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/packages/react-reconciler/src/ReactFiber.js b/packages/react-reconciler/src/ReactFiber.js
index 2b29ea79aae5b..de69a27c03451 100644
--- a/packages/react-reconciler/src/ReactFiber.js
+++ b/packages/react-reconciler/src/ReactFiber.js
@@ -35,6 +35,7 @@ import {
 } from 'shared/ReactTypeOfWork';
 import getComponentName from 'shared/getComponentName';
 
+import {isDevToolsPresent} from './ReactFiberDevToolsHook';
 import {NoWork} from './ReactFiberExpirationTime';
 import {NoContext, AsyncMode, ProfileMode, StrictMode} from './ReactTypeOfMode';
 import {
@@ -400,6 +401,13 @@ export function createFiberFromElement(
     }
   }
 
+  if (enableProfilerTimer && isDevToolsPresent) {
+    // Always collect profile timings when DevTools are present.
+    // This enables DevTools to start capturing timing at any point–
+    // Without some nodes in the tree having empty base times.
+    mode |= ProfileMode;
+  }
+
   fiber = createFiber(fiberTag, pendingProps, key, mode);
   fiber.type = type;
   fiber.expirationTime = expirationTime;
diff --git a/packages/react-reconciler/src/ReactFiberDevToolsHook.js b/packages/react-reconciler/src/ReactFiberDevToolsHook.js
index dd58854070103..4995978b11d60 100644
--- a/packages/react-reconciler/src/ReactFiberDevToolsHook.js
+++ b/packages/react-reconciler/src/ReactFiberDevToolsHook.js
@@ -31,6 +31,9 @@ function catchErrors(fn) {
   };
 }
 
+export const isDevToolsPresent =
+  typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ !== 'undefined';
+
 export function injectInternals(internals: Object): boolean {
   if (typeof __REACT_DEVTOOLS_GLOBAL_HOOK__ === 'undefined') {
     // No DevTools

From b2a6d5adeda5ede611bcb75bf02a4552639be0f1 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 15 Jun 2018 17:41:45 -0700
Subject: [PATCH 03/13] Added feature flag to control DevTools injection

---
 packages/react-dom/src/client/ReactDOM.js     | 57 ++++++++++---------
 .../react-native-renderer/src/ReactFabric.js  | 18 +++---
 .../src/ReactNativeRenderer.js                | 18 +++---
 .../src/ReactFiberReconciler.js               |  4 ++
 .../src/ReactTestHostConfig.js                |  9 +--
 .../src/ReactTestRenderer.js                  | 16 +++---
 .../src/ReactTestRendererComponentTree.js     | 19 -------
 ...ofilerDevToolsIntegration-test.internal.js |  3 +
 packages/shared/ReactFeatureFlags.js          |  3 +
 .../ReactFeatureFlags.native-fabric-fb.js     |  1 +
 .../ReactFeatureFlags.native-fabric-oss.js    |  1 +
 .../forks/ReactFeatureFlags.native-fb.js      |  2 +
 .../forks/ReactFeatureFlags.native-oss.js     |  2 +
 .../forks/ReactFeatureFlags.persistent.js     |  1 +
 .../forks/ReactFeatureFlags.test-renderer.js  |  1 +
 .../shared/forks/ReactFeatureFlags.www.js     |  2 +
 16 files changed, 83 insertions(+), 74 deletions(-)

diff --git a/packages/react-dom/src/client/ReactDOM.js b/packages/react-dom/src/client/ReactDOM.js
index 363617fc7e701..c3c484fbed1df 100644
--- a/packages/react-dom/src/client/ReactDOM.js
+++ b/packages/react-dom/src/client/ReactDOM.js
@@ -32,6 +32,7 @@ import ReactVersion from 'shared/ReactVersion';
 import {ReactCurrentOwner} from 'shared/ReactGlobalSharedState';
 import getComponentName from 'shared/getComponentName';
 import invariant from 'shared/invariant';
+import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import lowPriorityWarning from 'shared/lowPriorityWarning';
 import warning from 'shared/warning';
 
@@ -760,34 +761,36 @@ ReactDOM.unstable_createRoot = function createRoot(
   return new ReactRoot(container, true, hydrate);
 };
 
-const foundDevTools = DOMRenderer.injectIntoDevTools({
-  findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
-  bundleType: __DEV__ ? 1 : 0,
-  version: ReactVersion,
-  rendererPackageName: 'react-dom',
-});
+if (supportDevToolsIfPresent) {
+  const foundDevTools = DOMRenderer.injectIntoDevTools({
+    findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
+    bundleType: __DEV__ ? 1 : 0,
+    version: ReactVersion,
+    rendererPackageName: 'react-dom',
+  });
 
-if (__DEV__) {
-  if (!foundDevTools && canUseDOM && window.top === window.self) {
-    // If we're in Chrome or Firefox, provide a download link if not installed.
-    if (
-      (navigator.userAgent.indexOf('Chrome') > -1 &&
-        navigator.userAgent.indexOf('Edge') === -1) ||
-      navigator.userAgent.indexOf('Firefox') > -1
-    ) {
-      const protocol = window.location.protocol;
-      // Don't warn in exotic cases like chrome-extension://.
-      if (/^(https?|file):$/.test(protocol)) {
-        console.info(
-          '%cDownload the React DevTools ' +
-            'for a better development experience: ' +
-            'https://fb.me/react-devtools' +
-            (protocol === 'file:'
-              ? '\nYou might need to use a local HTTP server (instead of file://): ' +
-                'https://fb.me/react-devtools-faq'
-              : ''),
-          'font-weight:bold',
-        );
+  if (__DEV__) {
+    if (!foundDevTools && canUseDOM && window.top === window.self) {
+      // If we're in Chrome or Firefox, provide a download link if not installed.
+      if (
+        (navigator.userAgent.indexOf('Chrome') > -1 &&
+          navigator.userAgent.indexOf('Edge') === -1) ||
+        navigator.userAgent.indexOf('Firefox') > -1
+      ) {
+        const protocol = window.location.protocol;
+        // Don't warn in exotic cases like chrome-extension://.
+        if (/^(https?|file):$/.test(protocol)) {
+          console.info(
+            '%cDownload the React DevTools ' +
+              'for a better development experience: ' +
+              'https://fb.me/react-devtools' +
+              (protocol === 'file:'
+                ? '\nYou might need to use a local HTTP server (instead of file://): ' +
+                  'https://fb.me/react-devtools-faq'
+                : ''),
+            'font-weight:bold',
+          );
+        }
       }
     }
   }
diff --git a/packages/react-native-renderer/src/ReactFabric.js b/packages/react-native-renderer/src/ReactFabric.js
index 63cc05480b532..7e449308f14c5 100644
--- a/packages/react-native-renderer/src/ReactFabric.js
+++ b/packages/react-native-renderer/src/ReactFabric.js
@@ -23,6 +23,7 @@ import ReactNativeComponent from './ReactNativeComponent';
 import * as ReactFabricComponentTree from './ReactFabricComponentTree';
 import {getInspectorDataForViewTag} from './ReactNativeFiberInspector';
 
+import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import {ReactCurrentOwner} from 'shared/ReactGlobalSharedState';
 import getComponentName from 'shared/getComponentName';
 import warning from 'shared/warning';
@@ -119,12 +120,15 @@ const ReactFabric: ReactFabricType = {
   },
 };
 
-ReactFabricRenderer.injectIntoDevTools({
-  findFiberByHostInstance: ReactFabricComponentTree.getClosestInstanceFromNode,
-  getInspectorDataForViewTag: getInspectorDataForViewTag,
-  bundleType: __DEV__ ? 1 : 0,
-  version: ReactVersion,
-  rendererPackageName: 'react-native-renderer',
-});
+if (supportDevToolsIfPresent) {
+  ReactFabricRenderer.injectIntoDevTools({
+    findFiberByHostInstance:
+      ReactFabricComponentTree.getClosestInstanceFromNode,
+    getInspectorDataForViewTag: getInspectorDataForViewTag,
+    bundleType: __DEV__ ? 1 : 0,
+    version: ReactVersion,
+    rendererPackageName: 'react-native-renderer',
+  });
+}
 
 export default ReactFabric;
diff --git a/packages/react-native-renderer/src/ReactNativeRenderer.js b/packages/react-native-renderer/src/ReactNativeRenderer.js
index 9ff1749c50b84..6cced1c2ff2ac 100644
--- a/packages/react-native-renderer/src/ReactNativeRenderer.js
+++ b/packages/react-native-renderer/src/ReactNativeRenderer.js
@@ -26,6 +26,7 @@ import ReactNativeComponent from './ReactNativeComponent';
 import * as ReactNativeComponentTree from './ReactNativeComponentTree';
 import {getInspectorDataForViewTag} from './ReactNativeFiberInspector';
 
+import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import {ReactCurrentOwner} from 'shared/ReactGlobalSharedState';
 import getComponentName from 'shared/getComponentName';
 import warning from 'shared/warning';
@@ -142,12 +143,15 @@ const ReactNativeRenderer: ReactNativeType = {
   },
 };
 
-ReactNativeFiberRenderer.injectIntoDevTools({
-  findFiberByHostInstance: ReactNativeComponentTree.getClosestInstanceFromNode,
-  getInspectorDataForViewTag: getInspectorDataForViewTag,
-  bundleType: __DEV__ ? 1 : 0,
-  version: ReactVersion,
-  rendererPackageName: 'react-native-renderer',
-});
+if (supportDevToolsIfPresent) {
+  ReactNativeFiberRenderer.injectIntoDevTools({
+    findFiberByHostInstance:
+      ReactNativeComponentTree.getClosestInstanceFromNode,
+    getInspectorDataForViewTag: getInspectorDataForViewTag,
+    bundleType: __DEV__ ? 1 : 0,
+    version: ReactVersion,
+    rendererPackageName: 'react-native-renderer',
+  });
+}
 
 export default ReactNativeRenderer;
diff --git a/packages/react-reconciler/src/ReactFiberReconciler.js b/packages/react-reconciler/src/ReactFiberReconciler.js
index 3e1c36866fc87..38d2fca8fa44d 100644
--- a/packages/react-reconciler/src/ReactFiberReconciler.js
+++ b/packages/react-reconciler/src/ReactFiberReconciler.js
@@ -15,6 +15,7 @@ import type {
   Container,
   PublicInstance,
 } from './ReactFiberHostConfig';
+import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import type {ReactNodeList} from 'shared/ReactTypes';
 import type {ExpirationTime} from './ReactFiberExpirationTime';
 
@@ -261,6 +262,9 @@ export function findHostInstanceWithNoPortals(
 }
 
 export function injectIntoDevTools(devToolsConfig: DevToolsConfig): boolean {
+  if (!supportDevToolsIfPresent) {
+    return false;
+  }
   const {findFiberByHostInstance} = devToolsConfig;
   return ReactFiberDevToolsHook.injectInternals({
     ...devToolsConfig,
diff --git a/packages/react-test-renderer/src/ReactTestHostConfig.js b/packages/react-test-renderer/src/ReactTestHostConfig.js
index 8215f2653f16b..1a1e74a1e27df 100644
--- a/packages/react-test-renderer/src/ReactTestHostConfig.js
+++ b/packages/react-test-renderer/src/ReactTestHostConfig.js
@@ -7,7 +7,6 @@
  * @flow
  */
 
-import {precacheFiberNode} from './ReactTestRendererComponentTree';
 import * as TestRendererScheduling from './ReactTestRendererScheduling';
 
 export type Type = string;
@@ -118,15 +117,13 @@ export function createInstance(
   hostContext: Object,
   internalInstanceHandle: Object,
 ): Instance {
-  const instance = {
+  return {
     type,
     props,
     children: [],
     rootContainerInstance,
     tag: 'INSTANCE',
   };
-  precacheFiberNode(internalInstanceHandle, instance);
-  return instance;
 }
 
 export function appendInitialChild(
@@ -175,12 +172,10 @@ export function createTextInstance(
   hostContext: Object,
   internalInstanceHandle: Object,
 ): TextInstance {
-  const textInstance = {
+  return {
     text,
     tag: 'TEXT',
   };
-  precacheFiberNode(internalInstanceHandle, textInstance);
-  return textInstance;
 }
 
 export const isPrimaryRenderer = true;
diff --git a/packages/react-test-renderer/src/ReactTestRenderer.js b/packages/react-test-renderer/src/ReactTestRenderer.js
index 993e272230711..bdbd6cf81ff6e 100644
--- a/packages/react-test-renderer/src/ReactTestRenderer.js
+++ b/packages/react-test-renderer/src/ReactTestRenderer.js
@@ -29,6 +29,7 @@ import {
   Profiler,
 } from 'shared/ReactTypeOfWork';
 import invariant from 'shared/invariant';
+import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import ReactVersion from 'shared/ReactVersion';
 
 import * as ReactTestHostConfig from './ReactTestHostConfig';
@@ -517,12 +518,13 @@ const ReactTestRendererFiber = {
 };
 
 // Enable ReactTestRenderer to be used to test DevTools integration.
-// TODO (bvaughn) Perhaps this injection should be hidden behind a feature flag?
-TestRenderer.injectIntoDevTools({
-  findFiberByHostInstance,
-  bundleType: __DEV__ ? 1 : 0,
-  version: ReactVersion,
-  rendererPackageName: 'react-test-renderer',
-});
+if (supportDevToolsIfPresent) {
+  TestRenderer.injectIntoDevTools({
+    findFiberByHostInstance,
+    bundleType: __DEV__ ? 1 : 0,
+    version: ReactVersion,
+    rendererPackageName: 'react-test-renderer',
+  });
+}
 
 export default ReactTestRendererFiber;
diff --git a/packages/react-test-renderer/src/ReactTestRendererComponentTree.js b/packages/react-test-renderer/src/ReactTestRendererComponentTree.js
index 35604686f3909..e69de29bb2d1d 100644
--- a/packages/react-test-renderer/src/ReactTestRendererComponentTree.js
+++ b/packages/react-test-renderer/src/ReactTestRendererComponentTree.js
@@ -1,19 +0,0 @@
-/**
- * Copyright (c) 2013-present, Facebook, Inc.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-const randomKey = Math.random()
-  .toString(36)
-  .slice(2);
-const internalInstanceKey = '__reactInternalInstance$' + randomKey;
-
-export function findFiberByHostInstance(node) {
-  return node[internalInstanceKey];
-}
-
-export function precacheFiberNode(hostInst, node) {
-  node[internalInstanceKey] = hostInst;
-}
diff --git a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
index 8da55c43e414b..d24934b4b16bc 100644
--- a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
+++ b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
@@ -11,6 +11,7 @@
 
 describe('ReactProfiler DevTools integrate', () => {
   let React;
+  let ReactFeatureFlags;
   let ReactTestRenderer;
   let AdvanceTime;
   let advanceTimeBy;
@@ -38,6 +39,8 @@ describe('ReactProfiler DevTools integrate', () => {
 
     jest.resetModules();
 
+    ReactFeatureFlags = require('shared/ReactFeatureFlags');
+    ReactFeatureFlags.supportDevToolsIfPresent = true;
     React = require('react');
     ReactTestRenderer = require('react-test-renderer');
 
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index b3d2b48500549..73849ae945143 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -39,6 +39,9 @@ export const warnAboutLegacyContextAPI = false;
 // Gather advanced timing metrics for Profiler subtrees.
 export const enableProfilerTimer = __PROFILE__;
 
+// If the DevTools hook is present, inject into it.
+export const supportDevToolsIfPresent = false;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
index bd557015195fb..7f31595054d8c 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
@@ -21,6 +21,7 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = __DEV__;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __DEV__;
+export const supportDevToolsIfPresent = true;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js b/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
index ea6c7cf6d9ec1..d823ea272e821 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
@@ -21,6 +21,7 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;
+export const supportDevToolsIfPresent = true;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index b0fdc77f3a51e..a368144c0d0e2 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -27,6 +27,8 @@ export const {
 export const enableUserTimingAPI = __DEV__;
 export const warnAboutLegacyContextAPI = __DEV__;
 
+export const supportDevToolsIfPresent = true;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index 3c2b19bf1b580..ba3b3868f5d75 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -22,6 +22,8 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const enableProfilerTimer = __PROFILE__;
 
+export const supportDevToolsIfPresent = true;
+
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');
diff --git a/packages/shared/forks/ReactFeatureFlags.persistent.js b/packages/shared/forks/ReactFeatureFlags.persistent.js
index 88773cf900b3b..2be18c9a186e5 100644
--- a/packages/shared/forks/ReactFeatureFlags.persistent.js
+++ b/packages/shared/forks/ReactFeatureFlags.persistent.js
@@ -21,6 +21,7 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = false;
+export const supportDevToolsIfPresent = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index 1bc79a7b3f440..c7199525b096c 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -21,6 +21,7 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;
+export const supportDevToolsIfPresent = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index a50191a17607b..2e0fa777c5767 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -32,6 +32,8 @@ export const warnAboutLegacyContextAPI = __DEV__;
 // as long as there is more than a single listener.
 export let enableUserTimingAPI = __DEV__;
 
+export const supportDevToolsIfPresent = true;
+
 let refCount = 0;
 export function addUserTimingListener() {
   if (__DEV__) {

From a12c0bbb001d41af379130a73b7e0d357cb15161 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 15 Jun 2018 17:46:00 -0700
Subject: [PATCH 04/13] Moved DevTools ProfileMode check to create-host
 function

---
 packages/react-reconciler/src/ReactFiber.js | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/packages/react-reconciler/src/ReactFiber.js b/packages/react-reconciler/src/ReactFiber.js
index de69a27c03451..7e5a9dd3d6194 100644
--- a/packages/react-reconciler/src/ReactFiber.js
+++ b/packages/react-reconciler/src/ReactFiber.js
@@ -346,7 +346,15 @@ export function createWorkInProgress(
 }
 
 export function createHostRootFiber(isAsync: boolean): Fiber {
-  const mode = isAsync ? AsyncMode | StrictMode : NoContext;
+  let mode = isAsync ? AsyncMode | StrictMode : NoContext;
+
+  if (enableProfilerTimer && isDevToolsPresent) {
+    // Always collect profile timings when DevTools are present.
+    // This enables DevTools to start capturing timing at any point–
+    // Without some nodes in the tree having empty base times.
+    mode |= ProfileMode;
+  }
+
   return createFiber(HostRoot, null, null, mode);
 }
 
@@ -401,13 +409,6 @@ export function createFiberFromElement(
     }
   }
 
-  if (enableProfilerTimer && isDevToolsPresent) {
-    // Always collect profile timings when DevTools are present.
-    // This enables DevTools to start capturing timing at any point–
-    // Without some nodes in the tree having empty base times.
-    mode |= ProfileMode;
-  }
-
   fiber = createFiber(fiberTag, pendingProps, key, mode);
   fiber.type = type;
   fiber.expirationTime = expirationTime;

From 6e9ee844253effa34d9aa44f4d3c472e59ba89d3 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 15 Jun 2018 17:47:11 -0700
Subject: [PATCH 05/13] Renamed test description

---
 .../ReactProfilerDevToolsIntegration-test.internal.js         | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
index d24934b4b16bc..51398104ae1d6 100644
--- a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
+++ b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
@@ -9,7 +9,7 @@
 
 'use strict';
 
-describe('ReactProfiler DevTools integrate', () => {
+describe('ReactProfiler DevTools integration', () => {
   let React;
   let ReactFeatureFlags;
   let ReactTestRenderer;
@@ -62,7 +62,7 @@ describe('ReactProfiler DevTools integrate', () => {
     };
   });
 
-  it('should automatically profile all fibers if the DevTools hook is detected', () => {
+  it('should auto-Profile all fibers if the DevTools hook is detected', () => {
     const App = ({multiplier}) => {
       advanceTimeBy(2);
       return (

From 6546e32625778930254eec09eb2a585e59241f1c Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 15 Jun 2018 17:54:45 -0700
Subject: [PATCH 06/13] Removed unsupported method

---
 packages/react-test-renderer/src/ReactTestRenderer.js | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/packages/react-test-renderer/src/ReactTestRenderer.js b/packages/react-test-renderer/src/ReactTestRenderer.js
index bdbd6cf81ff6e..274871fb8b695 100644
--- a/packages/react-test-renderer/src/ReactTestRenderer.js
+++ b/packages/react-test-renderer/src/ReactTestRenderer.js
@@ -34,7 +34,6 @@ import ReactVersion from 'shared/ReactVersion';
 
 import * as ReactTestHostConfig from './ReactTestHostConfig';
 import * as TestRendererScheduling from './ReactTestRendererScheduling';
-import {findFiberByHostInstance} from './ReactTestRendererComponentTree';
 
 type TestRendererOptions = {
   createNodeMock: (element: React$Element<any>) => any,
@@ -520,7 +519,11 @@ const ReactTestRendererFiber = {
 // Enable ReactTestRenderer to be used to test DevTools integration.
 if (supportDevToolsIfPresent) {
   TestRenderer.injectIntoDevTools({
-    findFiberByHostInstance,
+    findFiberByHostInstance: (() => {
+      throw new Error(
+        'TestRenderer does not support findFiberByHostInstance()',
+      );
+    }: any),
     bundleType: __DEV__ ? 1 : 0,
     version: ReactVersion,
     rendererPackageName: 'react-test-renderer',

From 8bfbbe320e335536bf1e5a0944e45ead3019ba2a Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 15 Jun 2018 18:29:38 -0700
Subject: [PATCH 07/13] Added missing feature flag to test

---
 .../__tests__/ReactProfilerDevToolsIntegration-test.internal.js  | 1 +
 1 file changed, 1 insertion(+)

diff --git a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
index 51398104ae1d6..5c9f9ffd89e99 100644
--- a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
+++ b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
@@ -40,6 +40,7 @@ describe('ReactProfiler DevTools integration', () => {
     jest.resetModules();
 
     ReactFeatureFlags = require('shared/ReactFeatureFlags');
+    ReactFeatureFlags.enableProfilerTimer = true;
     ReactFeatureFlags.supportDevToolsIfPresent = true;
     React = require('react');
     ReactTestRenderer = require('react-test-renderer');

From 7a3750052137a8d3cd1a7be99034b2ce0f0429af Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Sat, 16 Jun 2018 07:23:06 -0700
Subject: [PATCH 08/13] supportDevToolsIfPresent true for base feature flags
 file

---
 packages/shared/ReactFeatureFlags.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 73849ae945143..8f6b61715b774 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -40,7 +40,7 @@ export const warnAboutLegacyContextAPI = false;
 export const enableProfilerTimer = __PROFILE__;
 
 // If the DevTools hook is present, inject into it.
-export const supportDevToolsIfPresent = false;
+export const supportDevToolsIfPresent = true;
 
 // Only used in www builds.
 export function addUserTimingListener() {

From 3e22e597f916486c0523c4df4b0114635ac74324 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Sat, 16 Jun 2018 07:24:12 -0700
Subject: [PATCH 09/13] Remove treeBaseTime getter from test renderer

---
 packages/react-test-renderer/src/ReactTestRenderer.js         | 4 ----
 .../ReactProfilerDevToolsIntegration-test.internal.js         | 4 ++--
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/packages/react-test-renderer/src/ReactTestRenderer.js b/packages/react-test-renderer/src/ReactTestRenderer.js
index 274871fb8b695..563a9610185f5 100644
--- a/packages/react-test-renderer/src/ReactTestRenderer.js
+++ b/packages/react-test-renderer/src/ReactTestRenderer.js
@@ -281,10 +281,6 @@ class ReactTestInstance {
     return this._currentFiber().memoizedProps;
   }
 
-  get treeBaseTime(): number {
-    return this._currentFiber().treeBaseTime || 0;
-  }
-
   get parent(): ?ReactTestInstance {
     let parent = this._fiber.return;
     while (parent !== null) {
diff --git a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
index 5c9f9ffd89e99..cc12881fda379 100644
--- a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
+++ b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
@@ -93,7 +93,7 @@ describe('ReactProfiler DevTools integration', () => {
     // At this point, the base time should include both:
     // The time 2ms in the App component itself, and
     // The 10ms spend in the Profiler sub-tree beneath.
-    expect(rendered.root.findByType(App).treeBaseTime).toBe(12);
+    expect(rendered.root.findByType(App)._currentFiber().treeBaseTime).toBe(12);
 
     rendered.update(<App multiplier={2} />);
 
@@ -107,6 +107,6 @@ describe('ReactProfiler DevTools integration', () => {
     // At this point, the base time should include both:
     // The initial 9ms for the components that do not re-render, and
     // The updated 6ms for the component that does.
-    expect(rendered.root.findByType(App).treeBaseTime).toBe(15);
+    expect(rendered.root.findByType(App)._currentFiber().treeBaseTime).toBe(15);
   });
 });

From 36151d175c0b0cbcc5de33f2de3636de7f867643 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Tue, 19 Jun 2018 10:21:30 -0700
Subject: [PATCH 10/13] supportDevToolsIfPresent = true for persistent config

---
 packages/shared/forks/ReactFeatureFlags.persistent.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/shared/forks/ReactFeatureFlags.persistent.js b/packages/shared/forks/ReactFeatureFlags.persistent.js
index 2be18c9a186e5..d325d42b6b55a 100644
--- a/packages/shared/forks/ReactFeatureFlags.persistent.js
+++ b/packages/shared/forks/ReactFeatureFlags.persistent.js
@@ -21,7 +21,7 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = false;
-export const supportDevToolsIfPresent = false;
+export const supportDevToolsIfPresent = true;
 
 // Only used in www builds.
 export function addUserTimingListener() {

From 4a68804bc50db8616038d23e9101797fa34b438e Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Wed, 20 Jun 2018 08:54:10 -0700
Subject: [PATCH 11/13] Removed supportDevToolsIfPresent feature flag

---
 packages/react-dom/src/client/ReactDOM.js     | 57 +++++++++----------
 .../react-native-renderer/src/ReactFabric.js  | 18 +++---
 .../src/ReactNativeRenderer.js                | 18 +++---
 .../src/ReactFiberReconciler.js               |  4 --
 .../src/ReactTestRenderer.js                  | 21 +++----
 ...ofilerDevToolsIntegration-test.internal.js |  1 -
 packages/shared/ReactFeatureFlags.js          |  3 -
 .../ReactFeatureFlags.native-fabric-fb.js     |  1 -
 .../ReactFeatureFlags.native-fabric-oss.js    |  1 -
 .../forks/ReactFeatureFlags.native-fb.js      |  2 -
 .../forks/ReactFeatureFlags.native-oss.js     |  2 -
 .../forks/ReactFeatureFlags.persistent.js     |  1 -
 .../forks/ReactFeatureFlags.test-renderer.js  |  1 -
 .../shared/forks/ReactFeatureFlags.www.js     |  2 -
 14 files changed, 49 insertions(+), 83 deletions(-)

diff --git a/packages/react-dom/src/client/ReactDOM.js b/packages/react-dom/src/client/ReactDOM.js
index c3c484fbed1df..363617fc7e701 100644
--- a/packages/react-dom/src/client/ReactDOM.js
+++ b/packages/react-dom/src/client/ReactDOM.js
@@ -32,7 +32,6 @@ import ReactVersion from 'shared/ReactVersion';
 import {ReactCurrentOwner} from 'shared/ReactGlobalSharedState';
 import getComponentName from 'shared/getComponentName';
 import invariant from 'shared/invariant';
-import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import lowPriorityWarning from 'shared/lowPriorityWarning';
 import warning from 'shared/warning';
 
@@ -761,36 +760,34 @@ ReactDOM.unstable_createRoot = function createRoot(
   return new ReactRoot(container, true, hydrate);
 };
 
-if (supportDevToolsIfPresent) {
-  const foundDevTools = DOMRenderer.injectIntoDevTools({
-    findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
-    bundleType: __DEV__ ? 1 : 0,
-    version: ReactVersion,
-    rendererPackageName: 'react-dom',
-  });
+const foundDevTools = DOMRenderer.injectIntoDevTools({
+  findFiberByHostInstance: ReactDOMComponentTree.getClosestInstanceFromNode,
+  bundleType: __DEV__ ? 1 : 0,
+  version: ReactVersion,
+  rendererPackageName: 'react-dom',
+});
 
-  if (__DEV__) {
-    if (!foundDevTools && canUseDOM && window.top === window.self) {
-      // If we're in Chrome or Firefox, provide a download link if not installed.
-      if (
-        (navigator.userAgent.indexOf('Chrome') > -1 &&
-          navigator.userAgent.indexOf('Edge') === -1) ||
-        navigator.userAgent.indexOf('Firefox') > -1
-      ) {
-        const protocol = window.location.protocol;
-        // Don't warn in exotic cases like chrome-extension://.
-        if (/^(https?|file):$/.test(protocol)) {
-          console.info(
-            '%cDownload the React DevTools ' +
-              'for a better development experience: ' +
-              'https://fb.me/react-devtools' +
-              (protocol === 'file:'
-                ? '\nYou might need to use a local HTTP server (instead of file://): ' +
-                  'https://fb.me/react-devtools-faq'
-                : ''),
-            'font-weight:bold',
-          );
-        }
+if (__DEV__) {
+  if (!foundDevTools && canUseDOM && window.top === window.self) {
+    // If we're in Chrome or Firefox, provide a download link if not installed.
+    if (
+      (navigator.userAgent.indexOf('Chrome') > -1 &&
+        navigator.userAgent.indexOf('Edge') === -1) ||
+      navigator.userAgent.indexOf('Firefox') > -1
+    ) {
+      const protocol = window.location.protocol;
+      // Don't warn in exotic cases like chrome-extension://.
+      if (/^(https?|file):$/.test(protocol)) {
+        console.info(
+          '%cDownload the React DevTools ' +
+            'for a better development experience: ' +
+            'https://fb.me/react-devtools' +
+            (protocol === 'file:'
+              ? '\nYou might need to use a local HTTP server (instead of file://): ' +
+                'https://fb.me/react-devtools-faq'
+              : ''),
+          'font-weight:bold',
+        );
       }
     }
   }
diff --git a/packages/react-native-renderer/src/ReactFabric.js b/packages/react-native-renderer/src/ReactFabric.js
index 7e449308f14c5..63cc05480b532 100644
--- a/packages/react-native-renderer/src/ReactFabric.js
+++ b/packages/react-native-renderer/src/ReactFabric.js
@@ -23,7 +23,6 @@ import ReactNativeComponent from './ReactNativeComponent';
 import * as ReactFabricComponentTree from './ReactFabricComponentTree';
 import {getInspectorDataForViewTag} from './ReactNativeFiberInspector';
 
-import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import {ReactCurrentOwner} from 'shared/ReactGlobalSharedState';
 import getComponentName from 'shared/getComponentName';
 import warning from 'shared/warning';
@@ -120,15 +119,12 @@ const ReactFabric: ReactFabricType = {
   },
 };
 
-if (supportDevToolsIfPresent) {
-  ReactFabricRenderer.injectIntoDevTools({
-    findFiberByHostInstance:
-      ReactFabricComponentTree.getClosestInstanceFromNode,
-    getInspectorDataForViewTag: getInspectorDataForViewTag,
-    bundleType: __DEV__ ? 1 : 0,
-    version: ReactVersion,
-    rendererPackageName: 'react-native-renderer',
-  });
-}
+ReactFabricRenderer.injectIntoDevTools({
+  findFiberByHostInstance: ReactFabricComponentTree.getClosestInstanceFromNode,
+  getInspectorDataForViewTag: getInspectorDataForViewTag,
+  bundleType: __DEV__ ? 1 : 0,
+  version: ReactVersion,
+  rendererPackageName: 'react-native-renderer',
+});
 
 export default ReactFabric;
diff --git a/packages/react-native-renderer/src/ReactNativeRenderer.js b/packages/react-native-renderer/src/ReactNativeRenderer.js
index 6cced1c2ff2ac..9ff1749c50b84 100644
--- a/packages/react-native-renderer/src/ReactNativeRenderer.js
+++ b/packages/react-native-renderer/src/ReactNativeRenderer.js
@@ -26,7 +26,6 @@ import ReactNativeComponent from './ReactNativeComponent';
 import * as ReactNativeComponentTree from './ReactNativeComponentTree';
 import {getInspectorDataForViewTag} from './ReactNativeFiberInspector';
 
-import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import {ReactCurrentOwner} from 'shared/ReactGlobalSharedState';
 import getComponentName from 'shared/getComponentName';
 import warning from 'shared/warning';
@@ -143,15 +142,12 @@ const ReactNativeRenderer: ReactNativeType = {
   },
 };
 
-if (supportDevToolsIfPresent) {
-  ReactNativeFiberRenderer.injectIntoDevTools({
-    findFiberByHostInstance:
-      ReactNativeComponentTree.getClosestInstanceFromNode,
-    getInspectorDataForViewTag: getInspectorDataForViewTag,
-    bundleType: __DEV__ ? 1 : 0,
-    version: ReactVersion,
-    rendererPackageName: 'react-native-renderer',
-  });
-}
+ReactNativeFiberRenderer.injectIntoDevTools({
+  findFiberByHostInstance: ReactNativeComponentTree.getClosestInstanceFromNode,
+  getInspectorDataForViewTag: getInspectorDataForViewTag,
+  bundleType: __DEV__ ? 1 : 0,
+  version: ReactVersion,
+  rendererPackageName: 'react-native-renderer',
+});
 
 export default ReactNativeRenderer;
diff --git a/packages/react-reconciler/src/ReactFiberReconciler.js b/packages/react-reconciler/src/ReactFiberReconciler.js
index 38d2fca8fa44d..3e1c36866fc87 100644
--- a/packages/react-reconciler/src/ReactFiberReconciler.js
+++ b/packages/react-reconciler/src/ReactFiberReconciler.js
@@ -15,7 +15,6 @@ import type {
   Container,
   PublicInstance,
 } from './ReactFiberHostConfig';
-import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import type {ReactNodeList} from 'shared/ReactTypes';
 import type {ExpirationTime} from './ReactFiberExpirationTime';
 
@@ -262,9 +261,6 @@ export function findHostInstanceWithNoPortals(
 }
 
 export function injectIntoDevTools(devToolsConfig: DevToolsConfig): boolean {
-  if (!supportDevToolsIfPresent) {
-    return false;
-  }
   const {findFiberByHostInstance} = devToolsConfig;
   return ReactFiberDevToolsHook.injectInternals({
     ...devToolsConfig,
diff --git a/packages/react-test-renderer/src/ReactTestRenderer.js b/packages/react-test-renderer/src/ReactTestRenderer.js
index 563a9610185f5..ed4c59fb38534 100644
--- a/packages/react-test-renderer/src/ReactTestRenderer.js
+++ b/packages/react-test-renderer/src/ReactTestRenderer.js
@@ -29,7 +29,6 @@ import {
   Profiler,
 } from 'shared/ReactTypeOfWork';
 import invariant from 'shared/invariant';
-import {supportDevToolsIfPresent} from 'shared/ReactFeatureFlags';
 import ReactVersion from 'shared/ReactVersion';
 
 import * as ReactTestHostConfig from './ReactTestHostConfig';
@@ -513,17 +512,13 @@ const ReactTestRendererFiber = {
 };
 
 // Enable ReactTestRenderer to be used to test DevTools integration.
-if (supportDevToolsIfPresent) {
-  TestRenderer.injectIntoDevTools({
-    findFiberByHostInstance: (() => {
-      throw new Error(
-        'TestRenderer does not support findFiberByHostInstance()',
-      );
-    }: any),
-    bundleType: __DEV__ ? 1 : 0,
-    version: ReactVersion,
-    rendererPackageName: 'react-test-renderer',
-  });
-}
+TestRenderer.injectIntoDevTools({
+  findFiberByHostInstance: (() => {
+    throw new Error('TestRenderer does not support findFiberByHostInstance()');
+  }: any),
+  bundleType: __DEV__ ? 1 : 0,
+  version: ReactVersion,
+  rendererPackageName: 'react-test-renderer',
+});
 
 export default ReactTestRendererFiber;
diff --git a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
index cc12881fda379..4c209b6d92f52 100644
--- a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
+++ b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
@@ -41,7 +41,6 @@ describe('ReactProfiler DevTools integration', () => {
 
     ReactFeatureFlags = require('shared/ReactFeatureFlags');
     ReactFeatureFlags.enableProfilerTimer = true;
-    ReactFeatureFlags.supportDevToolsIfPresent = true;
     React = require('react');
     ReactTestRenderer = require('react-test-renderer');
 
diff --git a/packages/shared/ReactFeatureFlags.js b/packages/shared/ReactFeatureFlags.js
index 8f6b61715b774..b3d2b48500549 100644
--- a/packages/shared/ReactFeatureFlags.js
+++ b/packages/shared/ReactFeatureFlags.js
@@ -39,9 +39,6 @@ export const warnAboutLegacyContextAPI = false;
 // Gather advanced timing metrics for Profiler subtrees.
 export const enableProfilerTimer = __PROFILE__;
 
-// If the DevTools hook is present, inject into it.
-export const supportDevToolsIfPresent = true;
-
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
index 7f31595054d8c..bd557015195fb 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fabric-fb.js
@@ -21,7 +21,6 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = __DEV__;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __DEV__;
-export const supportDevToolsIfPresent = true;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js b/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
index d823ea272e821..ea6c7cf6d9ec1 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fabric-oss.js
@@ -21,7 +21,6 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = __PROFILE__;
-export const supportDevToolsIfPresent = true;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.native-fb.js b/packages/shared/forks/ReactFeatureFlags.native-fb.js
index a368144c0d0e2..b0fdc77f3a51e 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-fb.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-fb.js
@@ -27,8 +27,6 @@ export const {
 export const enableUserTimingAPI = __DEV__;
 export const warnAboutLegacyContextAPI = __DEV__;
 
-export const supportDevToolsIfPresent = true;
-
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');
diff --git a/packages/shared/forks/ReactFeatureFlags.native-oss.js b/packages/shared/forks/ReactFeatureFlags.native-oss.js
index ba3b3868f5d75..3c2b19bf1b580 100644
--- a/packages/shared/forks/ReactFeatureFlags.native-oss.js
+++ b/packages/shared/forks/ReactFeatureFlags.native-oss.js
@@ -22,8 +22,6 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const enableProfilerTimer = __PROFILE__;
 
-export const supportDevToolsIfPresent = true;
-
 // Only used in www builds.
 export function addUserTimingListener() {
   invariant(false, 'Not implemented.');
diff --git a/packages/shared/forks/ReactFeatureFlags.persistent.js b/packages/shared/forks/ReactFeatureFlags.persistent.js
index d325d42b6b55a..88773cf900b3b 100644
--- a/packages/shared/forks/ReactFeatureFlags.persistent.js
+++ b/packages/shared/forks/ReactFeatureFlags.persistent.js
@@ -21,7 +21,6 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = __DEV__;
 export const enableProfilerTimer = false;
-export const supportDevToolsIfPresent = true;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.test-renderer.js b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
index c7199525b096c..1bc79a7b3f440 100644
--- a/packages/shared/forks/ReactFeatureFlags.test-renderer.js
+++ b/packages/shared/forks/ReactFeatureFlags.test-renderer.js
@@ -21,7 +21,6 @@ export const warnAboutDeprecatedLifecycles = false;
 export const warnAboutLegacyContextAPI = false;
 export const replayFailedUnitOfWorkWithInvokeGuardedCallback = false;
 export const enableProfilerTimer = false;
-export const supportDevToolsIfPresent = false;
 
 // Only used in www builds.
 export function addUserTimingListener() {
diff --git a/packages/shared/forks/ReactFeatureFlags.www.js b/packages/shared/forks/ReactFeatureFlags.www.js
index 2e0fa777c5767..a50191a17607b 100644
--- a/packages/shared/forks/ReactFeatureFlags.www.js
+++ b/packages/shared/forks/ReactFeatureFlags.www.js
@@ -32,8 +32,6 @@ export const warnAboutLegacyContextAPI = __DEV__;
 // as long as there is more than a single listener.
 export let enableUserTimingAPI = __DEV__;
 
-export const supportDevToolsIfPresent = true;
-
 let refCount = 0;
 export function addUserTimingListener() {
   if (__DEV__) {

From 2776f6fc879cdb118b1bee13bc4a43017d11ed09 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Wed, 20 Jun 2018 08:57:22 -0700
Subject: [PATCH 12/13] Removed unused ReactTestRendererComponentTree

---
 .../react-test-renderer/src/ReactTestRendererComponentTree.js     | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 delete mode 100644 packages/react-test-renderer/src/ReactTestRendererComponentTree.js

diff --git a/packages/react-test-renderer/src/ReactTestRendererComponentTree.js b/packages/react-test-renderer/src/ReactTestRendererComponentTree.js
deleted file mode 100644
index e69de29bb2d1d..0000000000000

From 854ef7efd192ee590ae1253576b406b67482bba6 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Wed, 20 Jun 2018 09:08:25 -0700
Subject: [PATCH 13/13] Fixed typo

---
 .../ReactProfilerDevToolsIntegration-test.internal.js         | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
index 4c209b6d92f52..6fc396405e78f 100644
--- a/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
+++ b/packages/react/src/__tests__/ReactProfilerDevToolsIntegration-test.internal.js
@@ -83,7 +83,7 @@ describe('ReactProfiler DevTools integration', () => {
 
     // Measure observable timing using the Profiler component.
     // The time spent in App (above the Profiler) won't be included in the durations,
-    // But needs to be acocunted for in the offset times.
+    // But needs to be accounted for in the offset times.
     expect(onRender).toHaveBeenCalledTimes(1);
     expect(onRender).toHaveBeenCalledWith('Profiler', 'mount', 10, 10, 2, 12);
     onRender.mockClear();
@@ -98,7 +98,7 @@ describe('ReactProfiler DevTools integration', () => {
 
     // Measure observable timing using the Profiler component.
     // The time spent in App (above the Profiler) won't be included in the durations,
-    // But needs to be acocunted for in the offset times.
+    // But needs to be accounted for in the offset times.
     expect(onRender).toHaveBeenCalledTimes(1);
     expect(onRender).toHaveBeenCalledWith('Profiler', 'update', 6, 13, 14, 20);