aura: Gesture event plumbing (skeleton).

ash/tooltips/tooltip_controller.cc

Index: ash/tooltips/tooltip_controller.cc
diff --git a/ash/tooltips/tooltip_controller.cc b/ash/tooltips/tooltip_controller.cc
index 9c77d2d7d895464b8fb8799c93c997d32f8ceb0a..f6cd200214ad3d80ced20f4f1a8691781ba37ab8 100644
--- a/ash/tooltips/tooltip_controller.cc
+++ b/ash/tooltips/tooltip_controller.cc
@@ -270,6 +270,12 @@ ui::TouchStatus TooltipController::PreHandleTouchEvent(
   return ui::TOUCH_STATUS_UNKNOWN;
 }
 
+ui::GestureStatus TooltipController::PreHandleGestureEvent(
+    aura::Window* target,
+    aura::GestureEvent* event) {
+  return ui::GESTURE_STATUS_UNKNOWN;
+}
+
 void TooltipController::OnWindowDestroyed(aura::Window* window) {
   if (tooltip_window_ == window) {
     tooltip_window_->RemoveObserver(this);