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

ui/aura/window_event_dispatcher.cc

Index: ui/aura/window_event_dispatcher.cc
diff --git a/ui/aura/window_event_dispatcher.cc b/ui/aura/window_event_dispatcher.cc
index 39dc1a489378812bad41fa551e3c957acef1ccf9..96e97aea6699afdedb604469988f71a468d8ef9a 100644
--- a/ui/aura/window_event_dispatcher.cc
+++ b/ui/aura/window_event_dispatcher.cc
@@ -528,12 +528,11 @@ bool WindowEventDispatcher::CanDispatchToConsumer(
   return (consumer_window && consumer_window->GetRootWindow() == window());
 }
 
-void WindowEventDispatcher::DispatchCancelTouchEvent(
-    ui::GestureConsumer* raw_input_consumer,
-    ui::TouchEvent* event) {
-  // The touchcancel event's location is based on the last known location of
+void WindowEventDispatcher::DispatchSyntheticTouchEvent(ui::TouchEvent* event) {
+  // The synthetic event's location is based on the last known location of
   // the pointer, in dips. OnEventFromSource expects events with co-ordinates
   // in raw pixels, so we convert back to raw pixels here.
+  DCHECK(event->type() == ui::ET_TOUCH_CANCELLED);
   event->UpdateForRootTransform(host_->GetRootTransform());
   DispatchDetails details = OnEventFromSource(event);
   if (details.dispatcher_destroyed)