Remove after wakeup logic and replace PumpTask with Fences

third_party/WebKit/Source/platform/scheduler/child/idle_helper.h

 // 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.
 
 #ifndef THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_IDLE_HELPER_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_IDLE_HELPER_H_
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "platform/scheduler/base/cancelable_closure_holder.h"
 #include "platform/scheduler/base/task_queue_selector.h"
 #include "platform/scheduler/child/scheduler_helper.h"
 #include "public/platform/scheduler/child/single_thread_idle_task_runner.h"
 #include "public/platform/WebCommon.h"
 
 namespace blink {
 namespace scheduler {
 
 class SchedulerHelper;
 
-// Common scheduler functionality for Idle tasks.
+// The job of the IdleHelper is to run idle tasks when the system is otherwise
+// idle. Idle tasks should be optional work, with no guarantee they will be run
+// at all. Idle tasks are subject to three levels of throttling:
+//
+//   1. Both idle queues are run a BEST_EFFORT priority (i.e. only selected if
+//      there is nothing else to do.
+//   2. The idle queues are only enabled during an idle period.
+//   3. Idle tasks posted from within an idle task run in the next idle period.
+//      This is achieved by inserting a fence into the queue.
+//
+// There are two types of idle periods:
+//   1. Short idle period - typically less than 10ms run after begin main frame
+//      has finished, with the idle period ending at the compositor provided
+//      deadline.
+//   2. Long idle periods - typically up to 50ms when no frames are being
+//      produced.
+//
+// Idle tasks are supplied a deadline, and should endeavor to finished before it
+// ends to avoid jank.
 class BLINK_PLATFORM_EXPORT IdleHelper
     : public base::MessageLoop::TaskObserver,
       public SingleThreadIdleTaskRunner::Delegate {
  public:
   // Used to by scheduler implementations to customize idle behaviour.
   class BLINK_PLATFORM_EXPORT Delegate {
    public:
     Delegate();
     virtual ~Delegate();
 
@@ skipping 182 matching lines @@
   base::WeakPtr<IdleHelper> weak_idle_helper_ptr_;
   base::WeakPtrFactory<IdleHelper> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(IdleHelper);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_CHILD_IDLE_HELPER_H_