[POC; Not for Review] Don't use PostTask queueing between compositor and main thread.

content/common/input/web_input_event_traits.cc

 // Copyright 2013 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.
 
 #include "content/common/input/web_input_event_traits.h"
 
 #include <bitset>
 #include <limits>
 
 #include "base/logging.h"
@@ skipping 472 matching lines @@
 void WebInputEventTraits::Coalesce(const WebInputEvent& event_to_coalesce,
                                    WebInputEvent* event) {
   DCHECK(event);
   Apply(WebInputEventCoalesce(), event->type, event_to_coalesce, event);
 }
 
 bool WebInputEventTraits::ShouldBlockEventStream(const WebInputEvent& event) {
   switch (event.type) {
     case WebInputEvent::MouseDown:
     case WebInputEvent::MouseUp:
+    case WebInputEvent::MouseMove:

[tdresser, 2016/05/30 14:05:32]

Will we still coalesce these correctly now? Or will we end up sending every
mousemove all the way to the renderer?

[dtapuska, 2016/06/01 18:22:53]

Mouse moves will go to the compositor and will be unthrottled. Essentially no
coalescing in the browser anymore.

Alternatively I could change this so it does block but mark them as handled in
the compositor (that is likely better).

     case WebInputEvent::MouseEnter:
     case WebInputEvent::MouseLeave:
     case WebInputEvent::ContextMenu:
     case WebInputEvent::GestureScrollBegin:
     case WebInputEvent::GestureScrollEnd:
     case WebInputEvent::GestureShowPress:
     case WebInputEvent::GestureTapUnconfirmed:
     case WebInputEvent::GestureTapDown:
     case WebInputEvent::GestureTapCancel:
     case WebInputEvent::GesturePinchBegin:
@@ skipping 24 matching lines @@
 
 uint32_t WebInputEventTraits::GetUniqueTouchEventId(
     const WebInputEvent& event) {
   if (WebInputEvent::isTouchEventType(event.type)) {
     return static_cast<const WebTouchEvent&>(event).uniqueTouchEventId;
   }
   return 0U;
 }
 
 }  // namespace content