scheduler: Post high priority tasks directly to the message loop

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 57 matching lines @@
     enum SchedulerPolicy {
         Normal,
         CompositorPriority,
     };
 
     Scheduler();
     virtual ~Scheduler();
 
     void scheduleIdleTask(const TraceLocation&, const IdleTask&);
     void postHighPriorityTaskInternal(const TraceLocation&, const Task&, const char* traceName);
+    void didRunHighPriorityTask();
 
     static void sharedTimerAdapter();
 
     // Start of main thread only members -----------------------------------
 
     // Only does work in CompositorPriority mode. Returns true if any work was done.
     bool runPendingHighPriorityTasksIfInCompositorPriority();
 
     // Returns true if any work was done.
-    bool swapQueuesAndRunPendingTasks();
-
-    void swapQueuesRunPendingTasksAndAllowHighPriorityTaskRunnerPosting();
-
-    // Returns true if any work was done.
     bool executeHighPriorityTasks(Deque<TracedTask>&);
 
     // Return the current SchedulerPolicy.
     SchedulerPolicy schedulerPolicy() const;
 
-    void maybeEnterNormalSchedulerPolicy();
-
-    // Must be called while m_pendingTasksMutex is locked.
-    void maybePostMainThreadPendingHighPriorityTaskRunner();
+    void updatePolicy();
 
     void tickSharedTimer();
 
     void (*m_sharedTimerFunction)();
 
     // End of main thread only members -------------------------------------
 
-    bool hasPendingHighPriorityWork() const;
-
     void enterSchedulerPolicyLocked(SchedulerPolicy);
-
     void enterSchedulerPolicy(SchedulerPolicy);
 
     static Scheduler* s_sharedScheduler;
 
     WebThread* m_mainThread;
 
-    // This mutex protects calls to the pending task queue, m_highPriorityTaskRunnerPosted and
-    // m_compositorPriorityPolicyEndTimeSeconds.
-    Mutex m_pendingTasksMutex;
-    DoubleBufferedDeque<TracedTask> m_pendingHighPriorityTasks;
-    double m_compositorPriorityPolicyEndTimeSeconds;
-
     // Declared volatile as it is atomically incremented.
     volatile int m_highPriorityTaskCount;
 
     bool m_highPriorityTaskRunnerPosted;
 
-    // Don't access m_schedulerPolicy directly, use enterSchedulerPolicyLocked and SchedulerPolicy instead.
+    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