[GPU] Get GPU process running on the mac...

app/gfx/native_widget_types.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 APP_GFX_NATIVE_WIDGET_TYPES_H_
 #define APP_GFX_NATIVE_WIDGET_TYPES_H_
 
 #include "base/basictypes.h"
 #include "build/build_config.h"
 
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 #if defined(OS_WIN)
   typedef HWND PluginWindowHandle;
   const PluginWindowHandle kNullPluginWindow = NULL;
 #elif defined(USE_X11)
   typedef unsigned long PluginWindowHandle;
   const PluginWindowHandle kNullPluginWindow = 0;
 #else
   // On OS X we don't have windowed plugins.
   // We use a NULL/0 PluginWindowHandle in shared code to indicate there
   // is no window present, so mirror that behavior here.
-  typedef bool PluginWindowHandle;
-  const PluginWindowHandle kNullPluginWindow = false;
+  //
+  // The GPU plugin is currently an exception to this rule. As of this
+  // writing it uses some NPAPI infrastructure, and minimally we need
+  // to identify the plugin instance via this window handle. When the
+  // GPU plugin becomes a full-on GPU process, this typedef can be
+  // returned to a bool. For now we use a type large enough to hold a
+  // pointer on 64-bit architectures in case we need this capability.
+  typedef uint64 PluginWindowHandle;
+  const PluginWindowHandle kNullPluginWindow = 0;
 #endif
 
 }  // namespace gfx
 
 #endif  // APP_GFX_NATIVE_WIDGET_TYPES_H_