Bug 775448: Add gesture cancelling support during sync subframe scrolling r=cjones

gfx/layers/ipc/AsyncPanZoomController.cpp

@@ -148,7 +148,7 @@ AsyncPanZoomController::HandleInputEvent(const nsInputEvent& aEvent,
 nsEventStatus AsyncPanZoomController::HandleInputEvent(const InputData& aEvent) {
   nsEventStatus rv = nsEventStatus_eIgnore;
 
-  if (mGestureEventListener) {
+  if (mGestureEventListener && !mDisableNextTouchBatch) {
     nsEventStatus rv = mGestureEventListener->HandleInputEvent(aEvent);
     if (rv == nsEventStatus_eConsumeNoDefault)
       return rv;
@@ -823,6 +823,9 @@ void AsyncPanZoomController::NotifyDOMTouchListenerAdded() {
 
 void AsyncPanZoomController::CancelDefaultPanZoom() {
   mDisableNextTouchBatch = true;
+  if (mGestureEventListener) {
+    mGestureEventListener->CancelGesture();
+  }
 }
 
 }

gfx/layers/ipc/GestureEventListener.cpp

@@ -260,5 +260,10 @@ AsyncPanZoomController* GestureEventListener::GetAsyncPanZoomController() {
   return mAsyncPanZoomController;
 }
 
+void GestureEventListener::CancelGesture() {
+  mTouches.Clear();
+  mState = GESTURE_NONE;
+}
+
 }
 }

gfx/layers/ipc/GestureEventListener.h

@@ -47,6 +47,13 @@ public:
    */
   nsEventStatus HandleInputEvent(const InputData& aEvent);
 
+  /**
+   * Cancels any currently active gesture. May not properly handle situations
+   * that require extra work at the gesture's end, like a pinch which only
+   * requests a repaint once it has ended.
+   */
+  void CancelGesture();
+
   /**
    * Returns the AsyncPanZoomController stored on this class and used for
    * callbacks.