Use the scheduling mechanism provided by the platform

Source/platform/scheduler/Scheduler.h

Index: Source/platform/scheduler/Scheduler.h
diff --git a/Source/platform/scheduler/Scheduler.h b/Source/platform/scheduler/Scheduler.h
index e63eb192000c512045e941537901b791b6d1f611..62b08a69f0f1098aa97ad97e13f2f57f9e48767a 100644
--- a/Source/platform/scheduler/Scheduler.h
+++ b/Source/platform/scheduler/Scheduler.h
@@ -6,15 +6,12 @@
 #define Scheduler_h
 
 #include "platform/PlatformExport.h"
-#include "platform/scheduler/TracedTask.h"
-#include "wtf/DoubleBufferedDeque.h"
 #include "wtf/Functional.h"
 #include "wtf/Noncopyable.h"
-#include "wtf/ThreadingPrimitives.h"
 
 namespace blink {
-class WebThread;
-struct WebBeginFrameArgs;
+class TraceLocation;
+class WebScheduler;
 
 // 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
@@ -22,123 +19,27 @@ struct WebBeginFrameArgs;
 class PLATFORM_EXPORT Scheduler {
     WTF_MAKE_NONCOPYABLE(Scheduler);
 public:
-    typedef Function<void()> Task;
     // An IdleTask is passed a deadline in CLOCK_MONOTONIC seconds and is expected to complete before this deadline.
     typedef Function<void(double deadlineSeconds)> IdleTask;
 
     static Scheduler* shared();
-    static void initializeOnMainThread();
     static void shutdown();
 
-    // Called to notify about the start of a new frame.
-    void willBeginFrame(double estimatedNextBeginFrameSeconds);
-
-    // 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 postIpcTask(const TraceLocation&, const Task&);
-    void postTask(const TraceLocation&, const Task&); // For generic (low priority) tasks.
     // For non-critical tasks which may be reordered relative to other task types and may be starved
     // for an arbitrarily long time if no idle time is available.
     void postIdleTask(const TraceLocation&, const IdleTask&);
 
-    // Tells the scheduler that the system received an input event. This causes the scheduler to go into
-    // Compositor Priority mode for a short duration.
-    void didReceiveInputEvent();
-
     // 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.
+    // Must be called on the main thread.
     bool shouldYieldForHighPriorityWork() const;
 
-    // The shared timer can be used to schedule a periodic callback which may
-    // get preempted by higher priority work.
-    void setSharedTimerFiredFunction(void (*function)());
-    void setSharedTimerFireInterval(double);
-    void stopSharedTimer();
-
-    // Returns the deadline, in CLOCK_MONOTONIC seconds, which an idle task should
-    // finish by for the current frame.
-    double currentFrameDeadlineForIdleTasks() const;
-
 protected:
-    class MainThreadPendingTaskRunner;
-    class MainThreadPendingHighPriorityTaskRunner;
-    class MainThreadPendingIdleTaskRunner;
-    friend class MainThreadPendingTaskRunner;
-    friend class MainThreadPendingHighPriorityTaskRunner;
-
-    enum SchedulerPolicy {
-        Normal,
-        CompositorPriority,
-    };
-
-    Scheduler();
+    Scheduler(WebScheduler*);
     virtual ~Scheduler();
 
-    void postHighPriorityTaskInternal(const TraceLocation&, const Task&, const char* traceName);
-    void postIdleTaskInternal(const TraceLocation&, const IdleTask&, 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 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();
-
-    // 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 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;
+    WebScheduler* m_webScheduler;
 };
 
 } // namespace blink