aura: Gesture event plumbing (skeleton).

ui/aura/event_filter.h

Index: ui/aura/event_filter.h
diff --git a/ui/aura/event_filter.h b/ui/aura/event_filter.h
index da2c2d1059094bf31c5c75bc918868fd838e3007..91af22a400292bc17b0593212a7f746058804d1a 100644
--- a/ui/aura/event_filter.h
+++ b/ui/aura/event_filter.h
@@ -12,6 +12,7 @@
 
 namespace aura {
 
+class GestureEvent;
 class KeyEvent;
 class MouseEvent;
 class TouchEvent;
@@ -53,6 +54,11 @@ class AURA_EXPORT EventFilter {
   virtual ui::TouchStatus PreHandleTouchEvent(Window* target,
                                               TouchEvent* event) = 0;
 
+  // Returns a value other than ui::GESTURE_STATUS_UNKNOWN if the gesture is
+  // consumed.
+  virtual ui::GestureStatus PreHandleGestureEvent(Window* target,
+                                                  GestureEvent* event) = 0;
+
  protected:
   Window* owner() { return owner_; }