Revert "Remove Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite h…

…istogram."

This reverts commit 804d774.

Reason for revert: https://bugs.chromium.org/p/chromium/issues/detail?id=1440580 Issue 1440580: Chrome: Crash Report - blink::ChildURLLoaderFactoryBundle::CreateLoaderAndStart

Original change's description:
> Remove Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite histogram.
>
> Remove the entry from histograms.xml, the metric logging in resource_fetcher.cc and associated tests in resource_fetcher_test.cc.
>
>
> Bug: 1385063
> Change-Id: Ic94e11465b22d923a4d44289cb71fb60b888019b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4460611
> Reviewed-by: Takashi Toyoshima <toyoshim@chromium.org>
> Commit-Queue: Mathijs Affourtit <maffourtit@google.com>
> Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
> Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
> Cr-Commit-Position: refs/heads/main@{#1135168}

Bug: 1385063
Change-Id: Ib4b0fea722ea6ca253fc4078266e29acdffd3ec6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4484559
Owners-Override: Srinivas Sista <srinivassista@chromium.org>
Reviewed-by: Harry Souders <harrysouders@google.com>
Commit-Queue: Srinivas Sista <srinivassista@chromium.org>
Cr-Commit-Position: refs/branch-heads/5735@{#38}
Cr-Branched-From: 2f562e4-refs/heads/main@{#1135570}

third_party/blink/renderer/platform/loader/fetch/resource_fetcher.cc

@@ -928,6 +928,11 @@ void ResourceFetcher::UpdateMemoryCacheStats(
     RecordResourceHistogram("Preload.", factory.GetType(), policy);
   } else {
     RecordResourceHistogram("", factory.GetType(), policy);
+
+    // Log metrics to evaluate effectiveness of the memory cache if it was
+    // partitioned by the top-frame site.
+    if (same_top_frame_site_resource_cached)
+      RecordResourceHistogram("PerTopFrameSite.", factory.GetType(), policy);
   }
 
   // Aims to count Resource only referenced from MemoryCache (i.e. what would be

third_party/blink/renderer/platform/loader/fetch/resource_fetcher_test.cc

@@ -386,6 +386,9 @@ TEST_F(ResourceFetcherTest, MetricsPerTopFrameSite) {
   EXPECT_EQ(resource_1, resource_2);
 
   // Test histograms.
+  histogram_tester.ExpectTotalCount(
+      "Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite.Mock", 0);
+
   histogram_tester.ExpectTotalCount("Blink.MemoryCache.RevalidationPolicy.Mock",
                                     2);
 
@@ -397,7 +400,7 @@ TEST_F(ResourceFetcherTest, MetricsPerTopFrameSite) {
       0 /* RevalidationPolicy::kUse */, 1);
 
   // Now load the same resource with origin_b as top-frame site. The
-  // histograms should be incremented.
+  // PerTopFrameSite histogram should be incremented.
   auto* fetcher_3 = CreateFetcher();
   ResourceRequestHead request_head_3(url);
   scoped_refptr<const SecurityOrigin> foo_origin_b =
@@ -409,6 +412,11 @@ TEST_F(ResourceFetcherTest, MetricsPerTopFrameSite) {
   Resource* resource_3 =
       MockResource::Fetch(fetch_params_2, fetcher_3, nullptr);
   EXPECT_EQ(resource_1, resource_3);
+  histogram_tester.ExpectTotalCount(
+      "Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite.Mock", 1);
+  histogram_tester.ExpectBucketCount(
+      "Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite.Mock",
+      0 /* RevalidationPolicy::kUse */, 1);
   histogram_tester.ExpectTotalCount("Blink.MemoryCache.RevalidationPolicy.Mock",
                                     3);
   histogram_tester.ExpectBucketCount(
@@ -457,6 +465,9 @@ TEST_F(ResourceFetcherTest, MetricsPerTopFrameSiteOpaqueOrigins) {
   EXPECT_EQ(resource_1, resource_2);
 
   // Test histograms.
+  histogram_tester.ExpectTotalCount(
+      "Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite.Mock", 0);
+
   histogram_tester.ExpectTotalCount("Blink.MemoryCache.RevalidationPolicy.Mock",
                                     2);
 
@@ -468,7 +479,7 @@ TEST_F(ResourceFetcherTest, MetricsPerTopFrameSiteOpaqueOrigins) {
       0 /* RevalidationPolicy::kUse */, 1);
 
   // Now load the same resource with opaque_origin1 as top-frame site. The
-  // histograms should be incremented.
+  // PerTopFrameSite histogram should be incremented.
   auto* fetcher_3 = CreateFetcher();
   ResourceRequestHead request_head_3(url);
   request_head_3.SetTopFrameOrigin(opaque_origin2);
@@ -478,6 +489,11 @@ TEST_F(ResourceFetcherTest, MetricsPerTopFrameSiteOpaqueOrigins) {
   Resource* resource_3 =
       MockResource::Fetch(fetch_params_2, fetcher_3, nullptr);
   EXPECT_EQ(resource_1, resource_3);
+  histogram_tester.ExpectTotalCount(
+      "Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite.Mock", 1);
+  histogram_tester.ExpectBucketCount(
+      "Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite.Mock",
+      0 /* RevalidationPolicy::kUse */, 1);
   histogram_tester.ExpectTotalCount("Blink.MemoryCache.RevalidationPolicy.Mock",
                                     3);
   histogram_tester.ExpectBucketCount(

tools/metrics/histograms/metadata/blink/histograms.xml

@@ -2457,6 +2457,19 @@ chromium-metrics-reviews@google.com.
   <token key="ResourceType" variants="ResourceType"/>
 </histogram>
 
+<histogram
+    name="Blink.MemoryCache.RevalidationPolicy.PerTopFrameSite.{ResourceType}"
+    enum="RevalidationPolicy" expires_after="2021-12-26">
+  <owner>shivanisha@chromium.org</owner>
+  <owner>privacy-sandbox-dev@chromium.org</owner>
+  <summary>
+    RevalidationPolicy used for requests for each resource type. Logged only if
+    the resource is found in the memory cache and if the same top-frame site had
+    loaded this resource earlier.
+  </summary>
+  <token key="ResourceType" variants="ResourceType"/>
+</histogram>
+
 <histogram name="Blink.MemoryCache.RevalidationPolicy.Preload.{ResourceType}"
     enum="RevalidationPolicy" expires_after="2023-10-01">
   <owner>hiroshige@chromium.org</owner>