Make IdleTimeEstimator ignore nested tasks

components/scheduler/renderer/idle_time_estimator.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/scheduler/renderer/idle_time_estimator.h"
 
 #include "base/time/default_tick_clock.h"
 
 namespace scheduler {
 
@@ skipping 18 matching lines @@
     base::TimeDelta compositor_frame_interval) const {
   base::TimeDelta expected_compositor_task_runtime_ =
       per_frame_compositor_task_runtime_.Percentile(estimation_percentile_);
   return std::max(base::TimeDelta(), compositor_frame_interval -
                                          expected_compositor_task_runtime_);
 }
 
 void IdleTimeEstimator::DidCommitFrameToCompositor() {
   // This will run inside of a WillProcessTask / DidProcessTask pair, let
   // DidProcessTask know a frame was comitted.
-  did_commit_ = true;
+  if (nesting_level_ == 1)
+    did_commit_ = true;
 }
 
 void IdleTimeEstimator::Clear() {
   task_start_time_ = base::TimeTicks();
   prev_commit_time_ = base::TimeTicks();
   cumulative_compositor_runtime_ = base::TimeDelta();
   per_frame_compositor_task_runtime_.Clear();
   did_commit_ = false;
 }
 
 void IdleTimeEstimator::SetTimeSourceForTesting(
     scoped_ptr<base::TickClock> time_source) {
   time_source_ = time_source.Pass();
 }
 
 void IdleTimeEstimator::WillProcessTask(const base::PendingTask& pending_task) {
   nesting_level_++;
-  task_start_time_ = time_source_->NowTicks();
+  if (nesting_level_ == 1)
+    task_start_time_ = time_source_->NowTicks();
 }
 
 void IdleTimeEstimator::DidProcessTask(const base::PendingTask& pending_task) {
-  DCHECK_EQ(nesting_level_, 1);
+  nesting_level_--;

[Sami, 2015/10/16 10:52:11]

nit: DCHECK_GT(nesting_level_, 0);

[alex clarke (OOO till 29th), 2015/10/16 10:54:46]

Done.

+  if (nesting_level_ != 0)
+    return;
+
   cumulative_compositor_runtime_ += time_source_->NowTicks() - task_start_time_;
 
   if (did_commit_) {
     per_frame_compositor_task_runtime_.InsertSample(
         cumulative_compositor_runtime_);
     cumulative_compositor_runtime_ = base::TimeDelta();
     did_commit_ = false;
   }
-  nesting_level_--;
 }
 
 }  // namespace scheduler