Adds a TransportDIB::Id value that is explicitly invalid and use it when compositing

content/plugin/webplugin_proxy.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/plugin/webplugin_proxy.h"
 
 #include "build/build_config.h"
 
 #include "base/lazy_instance.h"
 #include "base/scoped_handle.h"
@@ skipping 394 matching lines @@
     int ack_key
 #endif
     ) {
   gfx::Rect old = delegate_->GetRect();
   gfx::Rect old_clip_rect = delegate_->GetClipRect();
   transparent_ = transparent;
 
   // Update the buffers before doing anything that could call into plugin code,
   // so that we don't process buffer changes out of order if plugins make
   // synchronous calls that lead to nested UpdateGeometry calls.
-  if (TransportDIB::is_valid(windowless_buffer)) {
+  if (TransportDIB::is_valid_handle(windowless_buffer)) {
     // The plugin's rect changed, so now we have a new buffer to draw into.
     SetWindowlessBuffer(windowless_buffer, background_buffer, window_rect);
   }
 
 #if defined(OS_MACOSX)
   delegate_->UpdateGeometryAndContext(window_rect, clip_rect,
                                       windowless_context_);
 #else
   delegate_->UpdateGeometry(window_rect, clip_rect);
 #endif
@@ skipping 221 matching lines @@
       resource_clients_.erase(index++);
     } else {
       index++;
     }
   }
 }
 
 void WebPluginProxy::URLRedirectResponse(bool allow, int resource_id) {
   Send(new PluginHostMsg_URLRedirectResponse(route_id_, allow, resource_id));
 }