[scheduler] Throttle background frames with 1% CPU limit

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

Index: third_party/WebKit/Source/platform/scheduler/renderer/web_frame_scheduler_impl.cc
diff --git a/third_party/WebKit/Source/platform/scheduler/renderer/web_frame_scheduler_impl.cc b/third_party/WebKit/Source/platform/scheduler/renderer/web_frame_scheduler_impl.cc
index 1fd96aeb5b86f08773944a9cbdf750ac3db5f5cd..79cb6810a87701360b0c8af07652ca079d4219fa 100644
--- a/third_party/WebKit/Source/platform/scheduler/renderer/web_frame_scheduler_impl.cc
+++ b/third_party/WebKit/Source/platform/scheduler/renderer/web_frame_scheduler_impl.cc
@@ -36,6 +36,12 @@ WebFrameSchedulerImpl::~WebFrameSchedulerImpl() {
   }
 
   if (timer_task_queue_) {
+    if (parent_web_view_scheduler_ &&
+        parent_web_view_scheduler_->background_time_budget_pool_) {
+      parent_web_view_scheduler_->background_time_budget_pool_->RemoveQueue(
+          renderer_scheduler_->tick_clock()->NowTicks(),
+          timer_task_queue_.get());
+    }
     timer_task_queue_->UnregisterTaskQueue();
     timer_task_queue_->SetBlameContext(nullptr);
   }
@@ -50,6 +56,13 @@ WebFrameSchedulerImpl::~WebFrameSchedulerImpl() {
 }
 
 void WebFrameSchedulerImpl::DetachFromWebViewScheduler() {
+  TaskQueueThrottler::TimeBudgetPool* time_budget_pool =

[Sami, 2016/09/27 17:11:56]

Why do we need to do this here and also the destructor?

[altimin, 2016/09/27 17:38:23]

Because:
a) We need to do it here because we're losing handle to
parent_web_view_scheduler_ here.
b) We need to do it in destructor because DetachFromWebViewScheduler might not
be called before destructor.

[Sami, 2016/09/29 09:32:29]

I see. Could we instead call DetachFromWebViewScheduler() conditionally in the
destructor?

[altimin, 2016/09/29 12:32:38]

It will be ugly. Lets just call RemoveTimerQueueFromBackgroundTimeBudgetPool
from both places.

+      parent_web_view_scheduler_->background_time_budget_pool_;
+  if (time_budget_pool && timer_task_queue_) {
+    time_budget_pool->RemoveQueue(renderer_scheduler_->tick_clock()->NowTicks(),
+                                  timer_task_queue_.get());
+  }
+
   parent_web_view_scheduler_ = nullptr;
 }
 
@@ -88,6 +101,14 @@ blink::WebTaskRunner* WebFrameSchedulerImpl::timerTaskRunner() {
     timer_task_queue_ =
         renderer_scheduler_->NewTimerTaskRunner("frame_timer_tq");
     timer_task_queue_->SetBlameContext(blame_context_);
+
+    TaskQueueThrottler::TimeBudgetPool* time_budget_pool =
+        parent_web_view_scheduler_->background_time_budget_pool_;
+    if (time_budget_pool) {
+      time_budget_pool->AddQueue(renderer_scheduler_->tick_clock()->NowTicks(),
+                                 timer_task_queue_.get());
+    }
+
     if (ShouldThrottleTimers()) {
       renderer_scheduler_->task_queue_throttler()->IncreaseThrottleRefCount(
           timer_task_queue_.get());