aura: Start using EventPrcessor interface for event dispatch.

ui/aura/root_window_unittest.cc

Index: ui/aura/root_window_unittest.cc
diff --git a/ui/aura/root_window_unittest.cc b/ui/aura/root_window_unittest.cc
index f5d13b9363990b643d97c725f296b00c29eddc4f..715240015824a7f2cf1b20755c77fee0b089ba64 100644
--- a/ui/aura/root_window_unittest.cc
+++ b/ui/aura/root_window_unittest.cc
@@ -631,9 +631,8 @@ TEST_F(RootWindowTest, MouseMovesHeld) {
   EXPECT_EQ("MOUSE_DRAGGED", EventTypesToString(filter->events()));
   filter->events().clear();
 
-  // However if another message comes in before the dispatch,
-  // the Check that on ReleasePointerMoves, held events are not dispatched
-  // immediately, but posted instead.
+  // However if another message comes in before the dispatch of the posted
+  // event, check that the posted event is dispatched before this new event.
   dispatcher()->HoldPointerMoves();
   dispatcher()->AsRootWindowHostDelegate()->OnHostMouseEvent(
       &mouse_dragged_event);