Have EventSender mouseups unwind better on cancellation during dragover.

components/test_runner/event_sender.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/test_runner/event_sender.h"
 
 #include <stddef.h>
 
 #include "base/logging.h"
 #include "base/macros.h"
@@ skipping 2576 matching lines @@
 
   last_click_time_sec_ = e.timeStampSeconds;
   last_click_pos_ = last_mouse_pos_;
 
   // If we're in a drag operation, complete it.
   if (current_drag_data_.isNull())
     return;
 
   WebPoint client_point(e.x, e.y);
   WebPoint screen_point(e.globalX, e.globalY);
-  FinishDragAndDrop(
-      e,
-      view_->dragTargetDragOver(
-          client_point,
-          screen_point,
-          current_drag_effects_allowed_,
-          e.modifiers));
+  blink::WebDragOperation drag_effect = view_->dragTargetDragOver(
+      client_point,
+      screen_point,
+      current_drag_effects_allowed_,
+      e.modifiers);
+
+  // Bail if dragover caused cancellation.
+  if (current_drag_data_.isNull())
+    return;
+
+  FinishDragAndDrop(e, drag_effect);
 }
 
 void EventSender::DoMouseMove(const WebMouseEvent& e) {
   last_mouse_pos_ = WebPoint(e.x, e.y);
 
   HandleInputEventOnViewOrPopup(e);
 
   if (pressed_button_ == WebMouseEvent::ButtonNone ||
       current_drag_data_.isNull()) {
     return;
@@ skipping 57 matching lines @@
   last_event_timestamp_ = event.timeStampSeconds;
 
   if (WebPagePopup* popup = view_->pagePopup()) {
     if (!WebInputEvent::isKeyboardEventType(event.type))
       return popup->handleInputEvent(event);
   }
   return view_->handleInputEvent(event);
 }
 
 }  // namespace test_runner