Adds a didReceiveInputEvent api to the blink scheduler

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 ead89bf3286a1c662b6b980ad84f09991cf30bad..5c91daf6c0e7395bf0487a996eb8cae938c8802b 100644
--- a/Source/platform/scheduler/Scheduler.h
+++ b/Source/platform/scheduler/Scheduler.h
@@ -43,6 +43,9 @@ public:
     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 low latency mode for a little while.
+    void didReceiveInputEvent();
+
     // Returns true if we're in low latency mode and 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.