PPAPI: Fix destructor ordering problem for main-thread message loop

ppapi/proxy/plugin_globals.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.
 
 #include "ppapi/proxy/plugin_globals.h"
 
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_sender.h"
 #include "ppapi/proxy/plugin_dispatcher.h"
 #include "ppapi/proxy/plugin_proxy_delegate.h"
@@ skipping 58 matching lines @@
 #if defined(ENABLE_PEPPER_THREADING)
   enable_threading_ = true;
 #else
   enable_threading_ = false;
 #endif
   DCHECK(!plugin_globals_);
 }
 
 PluginGlobals::~PluginGlobals() {
   DCHECK(plugin_globals_ == this || !plugin_globals_);
+  // Release the main-thread message loop. We should have the last reference
+  // count, so this will delete the MessageLoop resource. We do this before
+  // we clear plugin_globals_, because the Resource destructor tries to access
+  // this PluginGlobals.
+  DCHECK(!loop_for_main_thread_ || loop_for_main_thread_->HasOneRef());
+  loop_for_main_thread_ = NULL;
+
   plugin_globals_ = NULL;
 }
 
 ResourceTracker* PluginGlobals::GetResourceTracker() {
   return &plugin_resource_tracker_;
 }
 
 VarTracker* PluginGlobals::GetVarTracker() {
   return &plugin_var_tracker_;
 }
@@ skipping 82 matching lines @@
 MessageLoopResource* PluginGlobals::loop_for_main_thread() {
   return loop_for_main_thread_.get();
 }
 
 bool PluginGlobals::IsPluginGlobals() const {
   return true;
 }
 
 }  // namespace proxy
 }  // namespace ppapi