UMA Sampling heap profiler: Report sample weights.

Use CallStackProfile.Sample.count field for that.

BUG=878604

Change-Id: Ie64d4b173a6b41c0a46d582429b32336fa3fe0cc
Reviewed-on: https://chromium-review.googlesource.com/1197429
Commit-Queue: Alexei Filippov <alph@chromium.org>
Reviewed-by: Mike Wittman <wittman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#589755}

chrome/common/heap_profiler_controller.cc

@@ -115,8 +115,7 @@ void HeapProfilerController::RetrieveAndSendSnapshot() {
           module_cache.GetModuleForAddress(address);
       frames.emplace_back(address, module);
     }
-    // TODO(alph): Report sample weight.
-    profile_builder.OnSampleCompleted(std::move(frames));
+    profile_builder.OnSampleCompleted(std::move(frames), sample.total);
   }
 
   profile_builder.OnProfileCompleted(base::TimeDelta(), base::TimeDelta());

components/metrics/call_stack_profile_builder.cc

@@ -177,6 +177,12 @@ void CallStackProfileBuilder::RecordAnnotations() {
 
 void CallStackProfileBuilder::OnSampleCompleted(
     std::vector<base::StackSamplingProfiler::Frame> frames) {
+  OnSampleCompleted(std::move(frames), 1);
+}
+
+void CallStackProfileBuilder::OnSampleCompleted(
+    std::vector<base::StackSamplingProfiler::Frame> frames,
+    size_t count) {
   // Assemble sample_ from |frames| first.
   for (const auto& frame : frames) {
     const base::ModuleCache::Module& module(frame.module);
@@ -206,20 +212,21 @@ void CallStackProfileBuilder::OnSampleCompleted(
   if (existing_sample_index != -1) {
     CallStackProfile::Sample* sample_proto =
         proto_profile_.mutable_deprecated_sample(existing_sample_index);
-    sample_proto->set_count(sample_proto->count() + 1);
+    sample_proto->set_count(sample_proto->count() + count);
     return;
   }
 
   CallStackProfile::Sample* sample_proto =
       proto_profile_.add_deprecated_sample();
   CopySampleToProto(sample_, modules_, sample_proto);
-  sample_proto->set_count(1);
+  sample_proto->set_count(count);
   CopyAnnotationsToProto(sample_.process_milestones & ~milestones_,
                          sample_proto);
   milestones_ = sample_.process_milestones;
 
   sample_index_.insert(std::make_pair(
-      sample_, static_cast<int>(proto_profile_.deprecated_sample_size()) - 1));
+      std::move(sample_),
+      static_cast<int>(proto_profile_.deprecated_sample_size()) - 1));
 
   sample_ = Sample();
 }

components/metrics/call_stack_profile_builder.h

@@ -98,6 +98,11 @@ class CallStackProfileBuilder
   void OnProfileCompleted(base::TimeDelta profile_duration,
                           base::TimeDelta sampling_period) override;
 
+  // The function is used by sampling heap profiler. Its samples already come
+  // with different counts.
+  void OnSampleCompleted(std::vector<base::StackSamplingProfiler::Frame> frames,
+                         size_t count);
+
   // Sets the callback to use for reporting browser process profiles. This
   // indirection is required to avoid a dependency on unnecessary metrics code
   // in child processes.

components/metrics/call_stack_profile_builder_unittest.cc

@@ -196,7 +196,7 @@ TEST(CallStackProfileBuilderTest, SamplesDeduped) {
   CallStackProfileBuilder::SetProcessMilestone(0);
 
   profile_builder->RecordAnnotations();
-  profile_builder->OnSampleCompleted(frames);
+  profile_builder->OnSampleCompleted(frames, 42);
 
   profile_builder->RecordAnnotations();
   profile_builder->OnSampleCompleted(frames);
@@ -214,6 +214,7 @@ TEST(CallStackProfileBuilderTest, SamplesDeduped) {
 
   ASSERT_TRUE(proto.has_call_stack_profile());
   ASSERT_EQ(1, proto.call_stack_profile().deprecated_sample_size());
+  ASSERT_EQ(43, proto.call_stack_profile().deprecated_sample(0).count());
 }
 
 TEST(CallStackProfileBuilderTest, SamplesNotDeduped) {