aura: Remove event-dispatch methods from WindowTreeHostDelegate interface.

ash/sticky_keys/sticky_keys_overlay_unittest.cc

Index: ash/sticky_keys/sticky_keys_overlay_unittest.cc
diff --git a/ash/sticky_keys/sticky_keys_overlay_unittest.cc b/ash/sticky_keys/sticky_keys_overlay_unittest.cc
index de2d980e931f97346a13c597fb2b1f1593d0d37d..a5aecb41812c54d39e943fa81e0ea9702fa0a9c1 100644
--- a/ash/sticky_keys/sticky_keys_overlay_unittest.cc
+++ b/ash/sticky_keys/sticky_keys_overlay_unittest.cc
@@ -41,9 +41,9 @@ class StickyKeysOverlayTest : public test::AshTestBase {
     ui::Event::DispatcherApi dispatcher(&event);
     dispatcher.set_target(Shell::GetInstance()->GetPrimaryRootWindow());
 
-    aura::WindowTreeHostDelegate* delegate = Shell::GetPrimaryRootWindow()
-        ->GetDispatcher()->AsWindowTreeHostDelegate();
-    delegate->OnHostKeyEvent(&event);
+    ui::EventDispatchDetails details = Shell::GetPrimaryRootWindow()->
+        GetDispatcher()->OnEventFromSource(&event);
+    CHECK(!details.dispatcher_destroyed);
   }
 
   StickyKeysController* controller_;