aura: Gesture event plumbing (skeleton).

ash/wm/window_modality_controller.h

Index: ash/wm/window_modality_controller.h
diff --git a/ash/wm/window_modality_controller.h b/ash/wm/window_modality_controller.h
index 0b43965755fd4b9a607c1945bd624b9d17a48299..0251a77733c35d65f8da9e0e984e45e94c2c8378 100644
--- a/ash/wm/window_modality_controller.h
+++ b/ash/wm/window_modality_controller.h
@@ -31,6 +31,9 @@ class WindowModalityController : public aura::EventFilter {
                                    aura::MouseEvent* event) OVERRIDE;
   virtual ui::TouchStatus PreHandleTouchEvent(aura::Window* target,
                                               aura::TouchEvent* event) OVERRIDE;
+  virtual ui::GestureStatus PreHandleGestureEvent(
+      aura::Window* target,
+      aura::GestureEvent* event) OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(WindowModalityController);