Adds a didReceiveInputEvent api to the blink scheduler

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"
@@ skipping 25 matching lines @@
     // 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.
 
+    // 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.
     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();
@@ skipping 77 matching lines @@
     volatile int m_highPriorityTaskCount;
     bool m_highPriorityTaskRunnerPosted;
 
     // Don't access m_schedulerPolicy directly, use enterSchedulerPolicyLocked and SchedulerPolicy instead.
     volatile int m_schedulerPolicy;
 };
 
 } // namespace blink
 
 #endif // Scheduler_h