Fix deadlock between UI thread and drag and drop thread on Windows.

content/browser/web_contents/web_drag_source_win.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_BROWSER_WEB_CONTENTS_WEB_DRAG_SOURCE_WIN_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_DRAG_SOURCE_WIN_H_
 
 #include "base/basictypes.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "ui/base/dragdrop/drag_source_win.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/point.h"
 
+namespace ui {
+class OSExchangeData;
+}  // namespace ui
+
 namespace content {
 class RenderViewHost;
 class WebContents;
 
 // An IDropSource implementation for a WebContentsImpl. Handles notifications
 // sent by an active drag-drop operation as the user mouses over other drop
 // targets on their system. This object tells Windows whether or not the drag
 // should continue, and supplies the appropriate cursors.
 class WebDragSource : public ui::DragSourceWin,
                       public NotificationObserver {
  public:
   // Create a new DragSource for a given HWND and WebContents.
   WebDragSource(gfx::NativeWindow source_wnd, WebContents* web_contents);
   virtual ~WebDragSource();
 
   // NotificationObserver implementation.
   virtual void Observe(int type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   void set_effect(DWORD effect) { effect_ = effect; }
+  void set_data(ui::OSExchangeData* data) { data_ = data; }

[sky, 2013/04/26 22:10:22]

Document ownership.

[dcheng, 2013/04/26 22:20:10]

Done.

 
  protected:
   // ui::DragSourceWin
   virtual void OnDragSourceCancel();
   virtual void OnDragSourceDrop();
   virtual void OnDragSourceMove();
 
  private:
   // Cannot construct thusly.
   WebDragSource();
 
   // OnDragSourceDrop schedules its main work to be done after IDropTarget::Drop
   // by posting a task to this function.
   void DelayedOnDragSourceDrop();
 
   // Keep a reference to the window so we can translate the cursor position.
   gfx::NativeWindow source_wnd_;
 
   // We use this as a channel to the renderer to tell it about various drag
   // drop events that it needs to know about (such as when a drag operation it
   // initiated terminates).
   RenderViewHost* render_view_host_;
 
   NotificationRegistrar registrar_;
 
   DWORD effect_;
 
+  ui::OSExchangeData* data_;
+
   DISALLOW_COPY_AND_ASSIGN(WebDragSource);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_DRAG_SOURCE_WIN_H_