Make much of the proxy thread-safe with 1 great big lock.

ppapi/thunk/enter.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 "ppapi/thunk/enter.h"
 
+#include "base/lazy_instance.h"
 #include "ppapi/thunk/ppb_instance_api.h"
 #include "ppapi/thunk/resource_creation_api.h"
 
 namespace ppapi {
 namespace thunk {
 
 EnterResourceCreation::EnterResourceCreation(PP_Instance instance)
     : EnterFunctionNoLock<ResourceCreationAPI>(instance, true) {
 }
 
 EnterResourceCreation::~EnterResourceCreation() {
 }
 
 EnterInstance::EnterInstance(PP_Instance instance)
     : EnterFunctionNoLock<PPB_Instance_FunctionAPI>(instance, true) {
 }
 
 EnterInstance::~EnterInstance() {
 }
 
 }  // namespace thunk
 }  // namespace ppapi