[Jank]: Add renderer visibility metadata.

The event is useful in tracing. Now that we're looking at jank using
sampling profiler, we need similar annotation for stack samples.

Change-Id: I6987dcb7da856f4a2099479d16c3ca37fd9e113a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2144775Reviewed-by: François Doray <fdoray@chromium.org>
Reviewed-by: Mike Wittman <wittman@chromium.org>
Reviewed-by: Alexander Timin <altimin@chromium.org>
Commit-Queue: Etienne Pierre-Doray <etiennep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759733}

third_party/blink/renderer/platform/scheduler/DEPS

@@ -29,6 +29,7 @@ include_rules = [
   "+base/observer_list.h",
   "+base/optional.h",
   "+base/pending_task.h",
+  "+base/profiler/sample_metadata.h",
   "+base/run_loop.h",
   "+base/sequence_checker.h",
   "+base/single_thread_task_runner.h",

third_party/blink/renderer/platform/scheduler/main_thread/main_thread_scheduler_impl.cc

@@ -937,9 +937,12 @@ void MainThreadSchedulerImpl::SetRendererHidden(bool hidden) {
   if (hidden) {
     TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                  "MainThreadSchedulerImpl::OnRendererHidden");
+    main_thread_only().renderer_hidden_metadata.emplace(
+        "MainThreadSchedulerImpl.RendererHidden", /* is_hidden */ 1);
   } else {
     TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("renderer.scheduler"),
                  "MainThreadSchedulerImpl::OnRendererVisible");
+    main_thread_only().renderer_hidden_metadata.reset();
   }
   helper_.CheckOnValidThread();
   main_thread_only().renderer_hidden = hidden;

third_party/blink/renderer/platform/scheduler/main_thread/main_thread_scheduler_impl.h

@@ -16,6 +16,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/single_sample_metrics.h"
 #include "base/optional.h"
+#include "base/profiler/sample_metadata.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/task/sequence_manager/task_queue.h"
@@ -880,6 +881,7 @@ class PLATFORM_EXPORT MainThreadSchedulerImpl
     TraceableState<RAILMode, TracingCategoryName::kInfo>
         rail_mode_for_tracing;  // Don't use except for tracing.
     TraceableState<bool, TracingCategoryName::kTopLevel> renderer_hidden;
+    base::Optional<base::ScopedSampleMetadata> renderer_hidden_metadata;
     TraceableState<bool, TracingCategoryName::kTopLevel> renderer_backgrounded;
     TraceableState<bool, TracingCategoryName::kDefault>
         keep_active_fetch_or_worker;