PPAPI: Disallow blocking callbacks while handling a blocking message

ppapi/proxy/message_handler.cc

 // Copyright 2014 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 "ppapi/proxy/message_handler.h"
 
 #include "ipc/ipc_message.h"
 #include "ppapi/proxy/plugin_dispatcher.h"
 #include "ppapi/proxy/ppapi_messages.h"
 #include "ppapi/proxy/ppb_message_loop_proxy.h"
@@ skipping 21 matching lines @@
 
 void HandleBlockingMessageWrapper(HandleBlockingMessageFunc function,
                                   PP_Instance instance,
                                   void* user_data,
                                   ScopedPPVar message_data,
                                   scoped_ptr<IPC::Message> reply_msg) {
   PluginDispatcher* dispatcher = PluginDispatcher::GetForInstance(instance);
   if (!dispatcher)
     return;
   PP_Var result = PP_MakeUndefined();
+  MessageLoopResource::GetCurrent()->
+      set_currently_handling_blocking_message(true);
   CallWhileUnlocked(
       function, instance, user_data, &message_data.get(), &result);
+  MessageLoopResource::GetCurrent()->
+      set_currently_handling_blocking_message(false);
   PpapiMsg_PPPMessageHandler_HandleBlockingMessage::WriteReplyParams(
       reply_msg.get(),
       SerializedVarReturnValue::Convert(dispatcher, result),
       true /* was_handled */);
   dispatcher->Send(reply_msg.release());
 }
 
 // TODO(dmichael): Remove the 0_1 verions; crbug.com/414398
 void HandleMessageWrapper_0_1(HandleMessageFunc_0_1 function,
                               PP_Instance instance,
                               void* user_data,
                               ScopedPPVar message_data) {
   CallWhileUnlocked(function, instance, user_data, message_data.get());
 }
 
 void HandleBlockingMessageWrapper_0_1(HandleBlockingMessageFunc_0_1 function,
                                       PP_Instance instance,
                                       void* user_data,
                                       ScopedPPVar message_data,
                                       scoped_ptr<IPC::Message> reply_msg) {
   PluginDispatcher* dispatcher = PluginDispatcher::GetForInstance(instance);
   if (!dispatcher)
     return;
+  MessageLoopResource::GetCurrent()->
+      set_currently_handling_blocking_message(true);
   PP_Var return_value = CallWhileUnlocked(function,
                                           instance,
                                           user_data,
                                           message_data.get());
+  MessageLoopResource::GetCurrent()->
+      set_currently_handling_blocking_message(false);
   PpapiMsg_PPPMessageHandler_HandleBlockingMessage::WriteReplyParams(
       reply_msg.get(),
       SerializedVarReturnValue::Convert(dispatcher, return_value),
       true /* was_handled */);
   dispatcher->Send(reply_msg.release());
 }
 
 }  // namespace
 
 // static
@@ skipping 153 matching lines @@
     scoped_refptr<MessageLoopResource> message_loop)
     : instance_(instance),
       handler_if_(NULL),
       handler_if_0_1_(handler_if),
       user_data_(user_data),
       message_loop_(message_loop) {
 }
 
 }  // namespace proxy
 }  // namespace ppapi