Drag and drop cleans up touch sequences from the source window.

ui/events/gestures/gesture_recognizer.h

Index: ui/events/gestures/gesture_recognizer.h
diff --git a/ui/events/gestures/gesture_recognizer.h b/ui/events/gestures/gesture_recognizer.h
index 245685257ba215cdc4609b7cb73404f97a17df00..5d7b792980f39d12c586e5aeadfb9f6ec0a2287d 100644
--- a/ui/events/gestures/gesture_recognizer.h
+++ b/ui/events/gestures/gesture_recognizer.h
@@ -62,14 +62,18 @@ class EVENTS_EXPORT GestureRecognizer {
   // |not_cancelled| == nullptr, cancels all touches.
   virtual void CancelActiveTouchesExcept(GestureConsumer* not_cancelled) = 0;
 
-  // Makes |new_consumer| the target for events previously targeting
-  // |current_consumer|. Touches targeting all other targets are
-  // canceled. The caller is responsible for updating the state of the
-  // consumers to be aware of this transfer of control (there are no
-  // ENTERED/EXITED events).
-  virtual void TransferEventsTo(GestureConsumer* current_consumer,
+  // Transfer the gesture stream from the drag source (current_consumer) to the
+  // consumer used for dragging (new_consumer). This dispatches cancel events to
+  // |current_consumer| to ensure that its touch stream remains valid.
+  virtual void BeginDragAndDrop(GestureConsumer* current_consumer,
                                 GestureConsumer* new_consumer) = 0;
 
+  // Transfer the gesture stream from the drag source (current_consumer) to the
+  // consumer used for dragging (new_consumer). This doesn't dispatch cancel
+  // events to |current_consumer|.
+  virtual void BeginTabDrag(GestureConsumer* current_consumer,
+                            GestureConsumer* new_consumer) = 0;
+
   // If a gesture is underway for |consumer| |point| is set to the last touch
   // point and true is returned. If no touch events have been processed for
   // |consumer| false is returned and |point| is untouched.