[scheduler] Teach scheduler about audio state

third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc

Index: third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
index 5f5473e063b6fb024c50bfca4320a751adce8db6..b9553cbe0bef34ae19dfb167bd3c845198b74f99 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/renderer_scheduler_impl.cc
@@ -37,6 +37,8 @@ const double kShortIdlePeriodDurationPercentile = 50;
 // Amount of idle time left in a frame (as a ratio of the vsync interval) above
 // which main thread compositing can be considered fast.
 const double kFastCompositingIdleTimeThreshold = .2;
+// We do not throttle anything while audio is played and shortly after that.
+const int kThrottlingDelayAfterAudioIsPlayedInSeconds = 5;
 
 void ReportForegroundRendererTaskLoad(base::TimeTicks time, double load) {
   int load_percentage = static_cast<int>(load * 100);
@@ -157,6 +159,18 @@ RendererSchedulerImpl::MainThreadOnly::MainThreadOnly(
       foreground_main_thread_load_tracker(
           now,
           base::Bind(&ReportForegroundRendererTaskLoad)),
+      audio_playback_switch(
+          renderer_scheduler_impl->ControlTaskRunner().get(),
+          base::TimeDelta::FromSeconds(
+              kThrottlingDelayAfterAudioIsPlayedInSeconds),
+          base::Bind(&RendererSchedulerImpl::OnAudioStartedImpl,
+                     // We can't get weak pointer to renderer_scheduler here
+                     // but this callback is guaranteed to be called while
+                     // |audio_playback_switch| is alive, which guarantees that
+                     // renderer_scheduler is still alive.
+                     base::Unretained(renderer_scheduler_impl)),

[Sami, 2016/09/29 13:36:07]

Could we instead change things so that we can get a weak pointer here?  We could
construct the factory earlier for instance.

[altimin, 2016/09/29 16:29:43]

Note: per Chromium style guide weak pointer factory should be last member of the
class and you will get a lot of complains from compiler.

+          base::Bind(&RendererSchedulerImpl::OnAudioStoppedImpl,
+                     base::Unretained(renderer_scheduler_impl))),
       current_use_case(UseCase::NONE),
       timer_queue_suspend_count(0),
       navigation_task_expected_count(0),
@@ -476,6 +490,14 @@ void RendererSchedulerImpl::OnRendererForegrounded() {
   ResumeTimerQueueWhenForegrounded();
 }
 
+void RendererSchedulerImpl::OnAudioStarted() {
+  MainThreadOnly().audio_playback_switch.Enable();

[Sami, 2016/09/29 13:36:07]

These could use trace events I think.

+}
+
+void RendererSchedulerImpl::OnAudioStopped() {
+  MainThreadOnly().audio_playback_switch.Disable();
+}
+
 void RendererSchedulerImpl::SuspendRenderer() {
   helper_.CheckOnValidThread();
   DCHECK(MainThreadOnly().renderer_backgrounded);
@@ -1195,6 +1217,14 @@ void RendererSchedulerImpl::CreateTraceEventObjectSnapshotLocked() const {
       this, AsValueLocked(helper_.scheduler_tqm_delegate()->NowTicks()));
 }
 
+void RendererSchedulerImpl::OnAudioStartedImpl() {

[alex clarke (OOO till 29th), 2016/09/29 11:16:53]

I don't think we need these two functions, why not bind
task_queue_throttler()->SetIsAudioActive directly?

[altimin, 2016/09/29 16:29:43]

Done.

+  task_queue_throttler()->SetIsAudioActive(true);
+}
+
+void RendererSchedulerImpl::OnAudioStoppedImpl() {
+  task_queue_throttler()->SetIsAudioActive(false);
+}
+
 // static
 const char* RendererSchedulerImpl::ExpensiveTaskPolicyToString(
     ExpensiveTaskPolicy expensive_task_policy) {