Make package location customizable in dev mode

Summary:
@public
With this, you can determine the packager location at run time before we even try to load the bundle.

Changelog: [Android] [Added] - Packager location can be determined at run time

Reviewed By: makovkastar

Differential Revision: D18940087

fbshipit-source-id: fac99f28e119a4e7a2961b5504cfe7d2d409e8f7

ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManagerImpl.java

@@ -140,6 +140,7 @@ private enum ErrorType {
   private @Nullable ErrorType mLastErrorType;
   private @Nullable DevBundleDownloadListener mBundleDownloadListener;
   private @Nullable List<ErrorCustomizer> mErrorCustomizers;
+  private @Nullable PackagerLocationCustomizer mPackagerLocationCustomizer;
 
   private InspectorPackagerConnection.BundleStatus mBundleStatus;
 
@@ -877,8 +878,19 @@ public void handleReloadJS() {
   }
 
   @Override
-  public void isPackagerRunning(PackagerStatusCallback callback) {
-    mDevServerHelper.isPackagerRunning(callback);
+  public void isPackagerRunning(final PackagerStatusCallback callback) {
+    Runnable checkPackagerRunning =
+        new Runnable() {
+          @Override
+          public void run() {
+            mDevServerHelper.isPackagerRunning(callback);
+          }
+        };
+    if (mPackagerLocationCustomizer != null) {
+      mPackagerLocationCustomizer.run(checkPackagerRunning);
+    } else {
+      checkPackagerRunning.run();
+    }
   }
 
   @Override
@@ -1240,4 +1252,9 @@ private void reload() {
   private static String getReloadAppAction(Context context) {
     return context.getPackageName() + RELOAD_APP_ACTION_SUFFIX;
   }
+
+  @Override
+  public void setPackagerLocationCustomizer(PackagerLocationCustomizer packagerLocationCustomizer) {
+    mPackagerLocationCustomizer = packagerLocationCustomizer;
+  }
 }

ReactAndroid/src/main/java/com/facebook/react/devsupport/DisabledDevSupportManager.java

@@ -130,7 +130,7 @@ public void handleReloadJS() {}
   public void reloadJSFromServer(String bundleURL) {}
 
   @Override
-  public void isPackagerRunning(PackagerStatusCallback callback) {}
+  public void isPackagerRunning(final PackagerStatusCallback callback) {}
 
   @Override
   public @Nullable File downloadBundleResourceFromUrlSync(
@@ -151,6 +151,10 @@ public void isPackagerRunning(PackagerStatusCallback callback) {}
   @Override
   public void registerErrorCustomizer(ErrorCustomizer errorCustomizer) {}
 
+  @Override
+  public void setPackagerLocationCustomizer(
+      PackagerLocationCustomizer packagerLocationCustomizer) {}
+
   @Override
   public void handleException(Exception e) {
     mDefaultNativeModuleCallExceptionHandler.handleException(e);

ReactAndroid/src/main/java/com/facebook/react/devsupport/interfaces/DevSupportManager.java

@@ -89,4 +89,15 @@ public interface DevSupportManager extends NativeModuleCallExceptionHandler {
   StackFrame[] getLastErrorStack();
 
   void registerErrorCustomizer(ErrorCustomizer errorCustomizer);
+
+  /**
+   * The PackagerLocationCustomizer allows you to have a dynamic packager location that is
+   * determined right before loading the packager. Your customizer must call |callback|, as loading
+   * will be blocked waiting for it to resolve.
+   */
+  public interface PackagerLocationCustomizer {
+    void run(Runnable callback);
+  }
+
+  void setPackagerLocationCustomizer(PackagerLocationCustomizer packagerLocationCustomizer);
 }