[Android] Always insert a TouchCancel if window or tab focus is lost

ui/events/gesture_detection/gesture_provider.h

Index: ui/events/gesture_detection/gesture_provider.h
diff --git a/ui/events/gesture_detection/gesture_provider.h b/ui/events/gesture_detection/gesture_provider.h
index ad2c106b9753b3f30c006daea61b98ad144f913e..6da919301f3f6eb69eb22f7d4a73ebd741169df2 100644
--- a/ui/events/gesture_detection/gesture_provider.h
+++ b/ui/events/gesture_detection/gesture_provider.h
@@ -48,8 +48,9 @@ class GESTURE_DETECTION_EXPORT GestureProvider {
   // Cancel the current touch event sequence by sending ACTION_CANCEL, and
   // ignore all the subsequent events until the next ACTION_DOWN.
   // One example usecase is to stop processing the touch events when showing
-  // a context popup menu.
-  void CancelActiveTouchSequence();
+  // a context popup menu. Returns true if there was an active touch sequence at
+  // the time of cancellation.
+  bool CancelActiveTouchSequence();
 
   // Update whether multi-touch gestures are supported.
   void SetMultiTouchSupportEnabled(bool enabled);
@@ -79,6 +80,11 @@ class GESTURE_DETECTION_EXPORT GestureProvider {
   // whether double-tap is supported), see |Config.disable_click_delay|.
   bool IsClickDelayDisabled() const;
 
+  // May be NULL if there is no currently active touch sequence.
+  const ui::MotionEvent* current_down_event() const {
+    return current_down_event_.get();
+  }
+
  private:
   void InitGestureDetectors(const Config& config);