[Sanity Review] cc: Mark an event has not-handled if it didn't cause a scroll

Source/WebKit/chromium/src/WebCompositorInputHandlerImpl.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 101 matching lines @@
 }
 
 WebCompositorInputHandlerImpl::EventDisposition WebCompositorInputHandlerImpl::handleInputEventInternal(const WebInputEvent& event)
 {
     if (event.type == WebInputEvent::MouseWheel) {
         const WebMouseWheelEvent& wheelEvent = *static_cast<const WebMouseWheelEvent*>(&event);
         WebInputHandlerClient::ScrollStatus scrollStatus = m_inputHandlerClient->scrollBegin(WebPoint(wheelEvent.x, wheelEvent.y), WebInputHandlerClient::ScrollInputTypeWheel);
         switch (scrollStatus) {
         case WebInputHandlerClient::ScrollStatusStarted: {
             TRACE_EVENT_INSTANT2("cc", "WebCompositorInputHandlerImpl::handleInput wheel scroll", "deltaX", -wheelEvent.deltaX, "deltaY", -wheelEvent.deltaY);
-            m_inputHandlerClient->scrollBy(WebPoint(wheelEvent.x, wheelEvent.y), IntSize(-wheelEvent.deltaX, -wheelEvent.deltaY));
+            bool didScroll = m_inputHandlerClient->scrollBy(WebPoint(wheelEvent.x, wheelEvent.y), IntSize(-wheelEvent.deltaX, -wheelEvent.deltaY));
             m_inputHandlerClient->scrollEnd();
-            return DidHandle;
+            return didScroll ? DidHandle : DropEvent;
         }
         case WebInputHandlerClient::ScrollStatusIgnored:
             // FIXME: This should be DropEvent, but in cases where we fail to properly sync scrollability it's safer to send the
             // event to the main thread. Change back to DropEvent once we have synchronization bugs sorted out.
             return DidNotHandle; 
         case WebInputHandlerClient::ScrollStatusOnMainThread:
             return DidNotHandle;
         }
     } else if (event.type == WebInputEvent::GestureScrollBegin) {
         ASSERT(!m_gestureScrollStarted);
@@ skipping 12 matching lines @@
         case WebInputHandlerClient::ScrollStatusIgnored:
             return DropEvent;
         }
     } else if (event.type == WebInputEvent::GestureScrollUpdate) {
         ASSERT(m_expectScrollUpdateEnd);
 
         if (!m_gestureScrollStarted)
             return DidNotHandle;
 
         const WebGestureEvent& gestureEvent = *static_cast<const WebGestureEvent*>(&event);
-        m_inputHandlerClient->scrollBy(WebPoint(gestureEvent.x, gestureEvent.y),
+        bool didScroll = m_inputHandlerClient->scrollBy(WebPoint(gestureEvent.x, gestureEvent.y),
             IntSize(-gestureEvent.data.scrollUpdate.deltaX, -gestureEvent.data.scrollUpdate.deltaY));
-        return DidHandle;
+        return didScroll ? DidHandle : DropEvent;
     } else if (event.type == WebInputEvent::GestureScrollEnd) {
         ASSERT(m_expectScrollUpdateEnd);
 #ifndef NDEBUG
         m_expectScrollUpdateEnd = false;
 #endif
         if (!m_gestureScrollStarted)
             return DidNotHandle;
 
         m_inputHandlerClient->scrollEnd();
         m_gestureScrollStarted = false;
@@ skipping 135 matching lines @@
         // This can happen when flinging a page that contains a scrollable subarea that we can't
         // scroll on the thread if the fling starts outside the subarea but then is flung "under" the
         // pointer.
         m_client->transferActiveWheelFlingAnimation(m_wheelFlingParameters);
         cancelCurrentFling();
         break;
     }
 }
 
 }