[scheduler] Implement time-based cpu throttling.

third_party/WebKit/Source/platform/scheduler/renderer/throttled_time_domain.h

 // Copyright 2016 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.
 
 #ifndef THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_THROTTLED_TIME_DOMAIN_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_THROTTLED_TIME_DOMAIN_H_
 
 #include "base/macros.h"
 #include "platform/scheduler/base/real_time_domain.h"
 
 namespace blink {
 namespace scheduler {
 
 // A time domain for throttled tasks. behaves like an RealTimeDomain except it
-// relies on the owner (ThrottlingHelper) to schedule wakeups.
+// relies on the owner (TaskQueueThrottler) to schedule wakeups.
 class BLINK_PLATFORM_EXPORT ThrottledTimeDomain : public RealTimeDomain {
  public:
   ThrottledTimeDomain(TimeDomain::Observer* observer,
                       const char* tracing_category);
   ~ThrottledTimeDomain() override;
 
   // TimeDomain implementation:
   const char* GetName() const override;
   void RequestWakeup(base::TimeTicks now, base::TimeDelta delay) override;
   bool MaybeAdvanceTime() override;
 
   using TimeDomain::ClearExpiredWakeups;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ThrottledTimeDomain);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_THROTTLED_TIME_DOMAIN_H_