aura: Remove event-dispatch methods from WindowTreeHostDelegate interface.

ui/views/widget/widget_interactive_uitest.cc

Index: ui/views/widget/widget_interactive_uitest.cc
diff --git a/ui/views/widget/widget_interactive_uitest.cc b/ui/views/widget/widget_interactive_uitest.cc
index 3fd2509ecdb9123a98ba2ba72293a91d24ab70ba..9e688b51fc3f906a686293c047e3efb35285603e 100644
--- a/ui/views/widget/widget_interactive_uitest.cc
+++ b/ui/views/widget/widget_interactive_uitest.cc
@@ -780,8 +780,9 @@ TEST_F(WidgetCaptureTest, MAYBE_MouseEventDispatchedToRightWindow) {
   // |widget2| has capture, |widget1| should still get the event.
   ui::MouseEvent mouse_event(ui::ET_MOUSE_EXITED, gfx::Point(), gfx::Point(),
                              ui::EF_NONE, ui::EF_NONE);
-  widget1.GetNativeWindow()->GetDispatcher()->AsWindowTreeHostDelegate()->
-      OnHostMouseEvent(&mouse_event);
+  ui::EventDispatchDetails details = widget1.GetNativeWindow()->
+      GetDispatcher()->OnEventFromSource(&mouse_event);
+  ASSERT_FALSE(details.dispatcher_destroyed);
   EXPECT_TRUE(widget1.GetAndClearGotMouseEvent());
   EXPECT_FALSE(widget2.GetAndClearGotMouseEvent());
 }