scheduler: Tell the scheduler about frame timing

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/TraceLocation.h"
 #include "wtf/DoubleBufferedDeque.h"
 #include "wtf/Functional.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
+class WebThread;
+struct WebBeginFrameArgs;
 
 // The scheduler is an opinionated gateway for arranging work to be run on the
 // main thread. It decides which tasks get priority over others based on a
 // scheduling policy and the overall system state.
-class WebThread;
-
 class PLATFORM_EXPORT Scheduler {
     WTF_MAKE_NONCOPYABLE(Scheduler);
 public:
     typedef Function<void()> Task;
     // An IdleTask is passed an allotted time in CLOCK_MONOTONIC milliseconds and is expected to complete within this timeframe.
     typedef Function<void(double allottedTimeMs)> IdleTask;
 
     static Scheduler* shared();
     static void initializeOnMainThread();
     static void shutdown();
 
+    // Called to notify about the start of a new frame.
+    void willBeginFrame(const WebBeginFrameArgs&);
+
+    // Called to notify that a previously begun frame was committed.
+    void didCommitFrameToCompositor();
+
     // The following entrypoints are used to schedule different types of tasks
     // to be run on the main thread. They can be called from any thread.
     void postInputTask(const TraceLocation&, const Task&);
     void postCompositorTask(const TraceLocation&, const Task&);
     void postTask(const TraceLocation&, const Task&); // For generic (low priority) tasks.
     void postIdleTask(const TraceLocation&, const IdleTask&); // For non-critical tasks which may be reordered relative to other task types.
 
     // Returns true if there is high priority work pending on the main thread
     // and the caller should yield to let the scheduler service that work.
     // Can be called on any thread.
@@ skipping 54 matching lines @@
     Mutex m_pendingTasksMutex;
     DoubleBufferedDeque<TracedTask> m_pendingHighPriorityTasks;
 
     volatile int m_highPriorityTaskCount;
     bool m_highPriorityTaskRunnerPosted;
 };
 
 } // namespace blink
 
 #endif // Scheduler_h