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

content/common/input/web_input_event_traits.cc

Index: content/common/input/web_input_event_traits.cc
diff --git a/content/common/input/web_input_event_traits.cc b/content/common/input/web_input_event_traits.cc
index c94a2d40c9b1e170e412a954c1e0462e5e5dde5f..ebd28d3d68dcdcd5d90120fa79332b69455375f7 100644
--- a/content/common/input/web_input_event_traits.cc
+++ b/content/common/input/web_input_event_traits.cc
@@ -490,6 +490,7 @@ 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: