WebSocket Pepper API: fix data corruption at ReceiveMessage in NaCl

ppapi/native_client/src/shared/ppapi_proxy/browser_ppb_websocket_rpc_server.cc

 // Copyright (c) 2012 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.
 //
 // SRPC-abstraction wrappers around PPB_WebSocket functions.
 
 #include "native_client/src/include/nacl_scoped_ptr.h"
 #include "native_client/src/shared/ppapi_proxy/browser_callback.h"
 #include "native_client/src/shared/ppapi_proxy/browser_globals.h"
 #include "native_client/src/shared/ppapi_proxy/object_serialize.h"
@@ skipping 126 matching lines @@
     // outputs
     int32_t* pp_error) {
   NaClSrpcClosureRunner runner(done);
   rpc->result = NACL_SRPC_RESULT_APP_ERROR;
 
   PP_Var* callback_var = NULL;
   PP_CompletionCallback remote_callback =
       MakeRemoteCompletionCallback(rpc->channel, callback_id, &callback_var);
   if (NULL == remote_callback.func)
     return;
+  // TODO(toyoshim): Removing optional flag is easy way to expect asynchronous
+  // completion on the following PPBWebSocketInterface()->ReceiveMessage(). But
+  // from the viewpoint of performance, we should handle synchronous
+  // completion correctly.
+  remote_callback.flags &= ~PP_COMPLETIONCALLBACK_FLAG_OPTIONAL;
 
   // The callback is always invoked asynchronously for now, so it doesn't care
   // about re-entrancy.
   *pp_error = PPBWebSocketInterface()->ReceiveMessage(
       ws, callback_var, remote_callback);
   DebugPrintf("PPB_WebSocket::ReceiveMessage: pp_error=%"NACL_PRId32"\n",
       *pp_error);
-
+  CHECK(*pp_error != PP_OK);  // Should not complete synchronously
   if (*pp_error != PP_OK_COMPLETIONPENDING)
     DeleteRemoteCallbackInfo(remote_callback);
   rpc->result = NACL_SRPC_RESULT_OK;
 }
 
 void PpbWebSocketRpcServer::PPB_WebSocket_SendMessage(
     NaClSrpcRpc* rpc,
     NaClSrpcClosure* done,
     // inputs
     PP_Resource ws,
@@ skipping 149 matching lines @@
     char* url_bytes) {
   NaClSrpcClosureRunner runner(done);
   rpc->result = NACL_SRPC_RESULT_APP_ERROR;
 
   PP_Var url = PPBWebSocketInterface()->GetURL(ws);
   DebugPrintf("PPB_WebSocket::GetURL:: url.type=%d\n", url.type);
 
   if (SerializeTo(&url, url_bytes, url_size))
     rpc->result = NACL_SRPC_RESULT_OK;
 }