Modify the scheduler to queue idle work between idle periods.

Source/platform/scheduler/Scheduler.h

 // Copyright 2014 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 Scheduler_h
 #define Scheduler_h
 
 #include "platform/PlatformExport.h"
 #include "platform/scheduler/TracedTask.h"
 #include "wtf/DoubleBufferedDeque.h"
@@ skipping 79 matching lines @@
 
     // Only does work in CompositorPriority mode. Returns true if any work was done.
     bool runPendingHighPriorityTasksIfInCompositorPriority();
 
     // Returns true if an idle task was posted to the main thread for execution.
     bool maybePostMainThreadPendingIdleTask();
 
     // Only does work if canRunIdleTask. Returns true if any work was done.
     bool maybeRunPendingIdleTask();
 
-    PassOwnPtr<internal::TracedIdleTask> takeFirstPendingIdleTask();
-
     // Returns true if the scheduler can run idle tasks at this time.
     bool canRunIdleTask() const;
 
+    // Flush the incoming idle tasks to the end of the pending idle task queue.
+    void flushIncomingIdleTasks();
+
     // Return the current SchedulerPolicy.
     SchedulerPolicy schedulerPolicy() const;
 
     void updatePolicy();
 
     void tickSharedTimer();
 
     void (*m_sharedTimerFunction)();
 
     // End of main thread only members -------------------------------------
 
     void enterSchedulerPolicyLocked(SchedulerPolicy);
     void enterSchedulerPolicy(SchedulerPolicy);
 
     static Scheduler* s_sharedScheduler;
 
     WebThread* m_mainThread;
 
-    // This mutex protects calls to the pending idle task queue.
-    Mutex m_pendingIdleTasksMutex;
-    Deque<OwnPtr<internal::TracedIdleTask>> m_pendingIdleTasks;
+    // This mutex protects calls to the incoming idle task queue.
+    Mutex m_incomingIdleTasksMutex;
+    Deque<OwnPtr<internal::TracedIdleTask>> m_incomingIdleTasks;
 
     bool m_currentFrameCommitted;
     double m_estimatedNextBeginFrameSeconds;
+    Deque<OwnPtr<internal::TracedIdleTask>> m_pendingIdleTasks;
+
     // Declared volatile as it is atomically incremented.
     volatile int m_highPriorityTaskCount;
 
     bool m_highPriorityTaskRunnerPosted;
 
     Mutex m_policyStateMutex;
     double m_compositorPriorityPolicyEndTimeSeconds;
 
     // Don't access m_schedulerPolicy directly, use enterSchedulerPolicyLocked and schedulerPolicy instead.
     volatile int m_schedulerPolicy;
 };
 
 } // namespace blink
 
 #endif // Scheduler_h