[scheduler] Throttle default timer queue when renderer is backgrounded.

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 752e9a102cc6901281170bdc04c686c9ba2dd829..9b15c9cc38e2041b3fadf35e118173d53c671cd7 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
@@ -487,6 +487,8 @@ void RendererSchedulerImpl::OnRendererBackgrounded() {
 
   MainThreadOnly().renderer_backgrounded = true;
 
+  UpdatePolicy();
+
   base::TimeTicks now = tick_clock()->NowTicks();
   MainThreadOnly().foreground_main_thread_load_tracker.Pause(now);
   MainThreadOnly().background_main_thread_load_tracker.Resume(now);
@@ -513,6 +515,8 @@ void RendererSchedulerImpl::OnRendererForegrounded() {
   MainThreadOnly().renderer_backgrounded = false;
   MainThreadOnly().renderer_suspended = false;
 
+  UpdatePolicy();
+
   base::TimeTicks now = tick_clock()->NowTicks();
   MainThreadOnly().foreground_main_thread_load_tracker.Resume(now);
   MainThreadOnly().background_main_thread_load_tracker.Pause(now);
@@ -1073,6 +1077,11 @@ void RendererSchedulerImpl::UpdatePolicyLocked(UpdateType update_type) {
       ShouldDisableThrottlingBecauseOfAudio(now) ||
       MainThreadOnly().use_virtual_time;
 
+  // TODO(altimin): Consider adding default timer tq to background time
+  // budget pool.
+  if (MainThreadOnly().renderer_backgrounded)
+    new_policy.timer_queue_policy.time_domain_type = TimeDomainType::THROTTLED;
+
   // Tracing is done before the early out check, because it's quite possible we
   // will otherwise miss this information in traces.
   CreateTraceEventObjectSnapshotLocked();