Lazily create the clipboard owner window. CreateWindow can take ~.5ms, and w...

base/clipboard.h

 // Copyright (c) 2006-2008 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 BASE_CLIPBOARD_H_
 #define BASE_CLIPBOARD_H_
 
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 157 matching lines @@
   // Safely write to system clipboard. Free |handle| on failure.
   void WriteToClipboard(FormatType format, HANDLE handle);
 
   static void ParseBookmarkClipboardFormat(const std::wstring& bookmark,
                                            std::wstring* title,
                                            std::string* url);
 
   // Free a handle depending on its type (as intuited from format)
   static void FreeData(FormatType format, HANDLE data);
 
-  HWND clipboard_owner_;
+  // Return the window that should be the clipboard owner, creating it
+  // if neccessary.  Marked const for lazily initialization by const methods.
+  HWND GetClipboardWindow() const;
+
+  // Mark this as mutable so const methods can still do lazy initialization.

[Peter Kasting, 2008/11/25 06:46:13]

Nit: Should probably comment that no one should access this directly (unless
they don't want to create it, like the destructor).

Also probably don't need the explanation on mutable, it's sort of obvious, but
feel free to leave it if you think it adds clarity

+  mutable HWND clipboard_owner_;
 #elif defined(OS_LINUX)
   // Data is stored in the |clipboard_data_| map until it is saved to the system
   // clipboard. The Store* functions save data to the |clipboard_data_| map. The
   // SetGtkClipboard function replaces whatever is on the system clipboard with
   // the contents of |clipboard_data_|.
   // The Write* functions make a deep copy of the data passed to them an store
   // it in |clipboard_data_|.
 
   // Write changes to gtk clipboard.
   void SetGtkClipboard();
   // Free pointers in clipboard_data_ and clear() the map.
   void FreeTargetMap();
   // Insert a mapping into clipboard_data_.
   void InsertMapping(const char* key, char* data, size_t data_len);
 
   TargetMap* clipboard_data_;
   GtkClipboard* clipboard_;
 #endif
 
   DISALLOW_EVIL_CONSTRUCTORS(Clipboard);
 };
 
 #endif  // BASE_CLIPBOARD_H_