Ensure swap is performed before informing compositor.

ppapi/native_client/src/shared/ppapi_proxy/plugin_ppb_graphics_3d.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 "native_client/src/shared/ppapi_proxy/plugin_ppb_graphics_3d.h"
 
 #include "gpu/command_buffer/client/gles2_implementation.h"
 #include "native_client/src/shared/ppapi_proxy/command_buffer_nacl.h"
@@ skipping 220 matching lines @@
           transfer_buffer_id,
           false));
       return true;
     }
   }
   return false;
 }
 
 int32_t PluginGraphics3D::SwapBuffers(PP_Resource graphics3d_id,
                                       struct PP_CompletionCallback callback) {
-
   int32_t callback_id = CompletionCallbackTable::Get()->AddCallback(callback);
   if (callback_id == 0)  // Just like Chrome, for now disallow blocking calls.
     return PP_ERROR_BLOCKS_MAIN_THREAD;
 
+  impl()->SwapBuffers();

[nfullagar, 2011/11/23 22:51:18]

what's going to happen if the NaClSrpcError retval returns an error below? 
There will be a pending impl()->SwapBuffer() but the RPC failed?

   int32_t pp_error;
   NaClSrpcError retval =
       PpbGraphics3DRpcClient::PPB_Graphics3D_SwapBuffers(
           GetMainSrpcChannel(),
           graphics3d_id,
           callback_id,
           &pp_error);
   if (retval != NACL_SRPC_RESULT_OK)
     return PP_ERROR_FAILED;
 
   if ((PP_OK_COMPLETIONPENDING != pp_error) && (PP_OK != pp_error))
     return pp_error;
 
-  impl()->SwapBuffers();
   return PP_OK_COMPLETIONPENDING;
 }
 
 
 // static
 const PPB_Graphics3D* PluginGraphics3D::GetInterface() {
   static const PPB_Graphics3D intf = {
     &GetAttribMaxValue,
     &Create,
     &IsGraphics3D,
     &GetAttribs,
     &SetAttribs,
     &GetError,
     &ResizeBuffers,
     &SwapBuffs,
   };
   return &intf;
 }
 
 }  // namespace ppapi_proxy