Turned on PbufferImageTransportSurface as default image transport for vista and win 7 (not XP).

content/public/common/content_switches.cc

 // Copyright (c) 2011 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 "content/public/common/content_switches.h"
 
 namespace switches {
 
 // By default, file:// URIs cannot read other file:// URIs. This is an
 // override for developers who need the old behavior for testing.
@@ skipping 89 matching lines @@
     "disable-gpu-driver-bug-workarounds";
 
 // Disable the GPU process sandbox.
 const char kDisableGpuSandbox[]             = "disable-gpu-sandbox";
 
 // Suppresses hang monitor dialogs in renderer processes.  This may allow slow
 // unload handlers on a page to prevent the tab from closing, but the Task
 // Manager can be used to terminate the offending process in this case.
 const char kDisableHangMonitor[]            = "disable-hang-monitor";
 
+// Disable the use of an ImageTransportSurface. This means the GPU process
+// will present the rendered page rather than the browser process.
+const char kDisableImageTransportSurface[]  = "disable-image-transport-surface";
+
 // Disable the thread that crashes the GPU process if it stops responding to
 // messages.
 const char kDisableGpuWatchdog[]            = "disable-gpu-watchdog";
 
 // Prevent Java from running.
 const char kDisableJava[]                   = "disable-java";
 
 // Don't execute JavaScript (browser JS like the new tab page still runs).
 const char kDisableJavaScript[]             = "disable-javascript";
 
@@ skipping 429 matching lines @@
 // instead of NSS for SSL.
 const char kUseSystemSSL[]                  = "use-system-ssl";
 #endif
 
 #if !defined(OFFICIAL_BUILD)
 // Causes the renderer process to throw an assertion on launch.
 const char kRendererCheckFalseTest[]        = "renderer-check-false-test";
 #endif
 
 }  // namespace switches