Support dragging a virtual file out of the browser.

chrome/browser/views/tab_contents/tab_contents_drag_win.h

+// Copyright (c) 2009 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 CHROME_BROWSER_VIEWS_TAB_CONTENTS_TAB_CONTENTS_DRAG_WIN_H_
+#define CHROME_BROWSER_VIEWS_TAB_CONTENTS_TAB_CONTENTS_DRAG_WIN_H_
+
+#include "app/os_exchange_data_provider_win.h"
+#include "base/platform_thread.h"
+#include "base/ref_counted.h"
+#include "base/scoped_ptr.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebDragOperation.h"
+
+class DragDropThread;
+class TabContentsViewWin;
+class WebDragSource;
+struct WebDropData;
+
+// Windows-specific drag-and-drop handling in TabContentsView.
+// If we are dragging a virtual file out of the browser, we use a background
+// thread to do the drag-and-drop because we do not want to run nested
+// message loop in the UI thread. For all other cases, the drag-and-drop happens
+// in the UI thread.
+class TabContentsDragWin
+    : public DataObjectImpl::Observer,
+      public base::RefCountedThreadSafe<TabContentsDragWin> {
+ public:
+  explicit TabContentsDragWin(TabContentsViewWin* view);
+  virtual ~TabContentsDragWin();
+
+  // Called on UI thread.
+  void StartDragging(const WebDropData& drop_data,
+                     WebKit::WebDragOperationsMask ops);
+  void CancelDrag();
+
+  // DataObjectImpl::Observer implementation.
+  // Called on drag-and-drop thread.
+  virtual void OnWaitForData();
+  virtual void OnDataObjectDisposed();
+
+ private:
+  // Called on either UI thread or drag-and-drop thread.
+  void PrepareDragForDownload(const WebDropData& drop_data,
+                              OSExchangeData* data,
+                              const GURL& page_url,
+                              const std::string& page_encoding);
+  void PrepareDragForFileContents(const WebDropData& drop_data,
+                                  OSExchangeData* data);
+  void PrepareDragForUrl(const WebDropData& drop_data, OSExchangeData* data);
+  void DoDragging(const WebDropData& drop_data,
+                  WebKit::WebDragOperationsMask ops,
+                  const GURL& page_url,
+                  const std::string& page_encoding);
+
+  // Called on drag-and-drop thread.
+  void StartBackgroundDragging(const WebDropData& drop_data,
+                               WebKit::WebDragOperationsMask ops,
+                               const GURL& page_url,
+                               const std::string& page_encoding);
+  // Called on UI thread.
+  void EndDragging(bool restore_suspended_state);
+  void CloseThread();
+
+  // For debug check only. Access only on drag-and-drop thread.
+#ifndef NDEBUG
+  PlatformThreadId drag_drop_thread_id_;
+#endif
+
+  // All the member variables below are accessed on UI thread.
+
+  // Keep track of the TabContentsViewWin it is associated with.
+  TabContentsViewWin* view_;
+
+  // |drag_source_| is our callback interface passed to the system when we
+  // want to initiate a drag and drop operation.  We use it to tell if a
+  // drag operation is happening.
+  scoped_refptr<WebDragSource> drag_source_;
+
+  // The thread used by the drag-out download. This is because we want to avoid
+  // running nested message loop in main UI thread.
+  scoped_ptr<DragDropThread> drag_drop_thread_;
+
+  // The flag to guard that EndDragging is not called twice.
+  bool drag_ended_;
+
+  // Keep track of the old suspended state of the drop target.
+  bool old_drop_target_suspended_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(TabContentsDragWin);
+};
+
+
+#endif  // CHROME_BROWSER_VIEWS_TAB_CONTENTS_TAB_CONTENTS_DRAG_WIN_H_