Include timestamp with vsync-delineating input events

Source/Platform/chromium/public/WebInputHandlerClient.h

Index: Source/Platform/chromium/public/WebInputHandlerClient.h
diff --git a/Source/Platform/chromium/public/WebInputHandlerClient.h b/Source/Platform/chromium/public/WebInputHandlerClient.h
index 15eba89b66b6d8de216121b6816bce1da177b109..decb3af218cd8a744c0485c9992992b02c6586e8 100644
--- a/Source/Platform/chromium/public/WebInputHandlerClient.h
+++ b/Source/Platform/chromium/public/WebInputHandlerClient.h
@@ -84,8 +84,10 @@ public:
     // given WebPoint.
     virtual bool haveTouchEventHandlersAt(WebPoint) = 0;
 
-    // Indicate that the final input event for the current vsync interval was received.
-    virtual void didReceiveLastInputEventForVSync() { }
+    // Indicate that the final input event for the current vsync interval was
+    // received. The frame time is given in the same time base as
+    // monotonicallyIncreasingTime().
+    virtual void didReceiveLastInputEventForVSync(double frameTimeSeconds) { }
 
 protected:
     virtual ~WebInputHandlerClient() { }