Made MessagePump a non-thread safe class.

base/message_loop/message_loop_proxy_impl.h

 // 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.
 
 #ifndef BASE_MESSAGE_LOOP_MESSAGE_LOOP_PROXY_IMPL_H_
 #define BASE_MESSAGE_LOOP_MESSAGE_LOOP_PROXY_IMPL_H_
 
 #include "base/base_export.h"
-#include "base/message_loop/message_loop.h"
+#include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop_proxy.h"
-#include "base/synchronization/lock.h"
+#include "base/pending_task.h"
+#include "base/threading/platform_thread.h"
 
 namespace base {
+namespace internal {
+
+class IncomingTaskQueue;
 
 // A stock implementation of MessageLoopProxy that is created and managed by a
 // MessageLoop. For now a MessageLoopProxyImpl can only be created as part of a
 // MessageLoop.
 class BASE_EXPORT MessageLoopProxyImpl : public MessageLoopProxy {
  public:
+  explicit MessageLoopProxyImpl(
+      scoped_refptr<IncomingTaskQueue> incoming_queue);
+
   // MessageLoopProxy implementation
   virtual bool PostDelayedTask(const tracked_objects::Location& from_here,
                                const base::Closure& task,
                                base::TimeDelta delay) OVERRIDE;
   virtual bool PostNonNestableDelayedTask(
       const tracked_objects::Location& from_here,
       const base::Closure& task,
       base::TimeDelta delay) OVERRIDE;
   virtual bool RunsTasksOnCurrentThread() const OVERRIDE;
 
- protected:
+ private:
+  friend class RefCountedThreadSafe<MessageLoopProxyImpl>;
   virtual ~MessageLoopProxyImpl();
 
-  // Override OnDestruct so that we can delete the object on the target message
-  // loop if it still exists.
-  virtual void OnDestruct() const OVERRIDE;
+  // THe incoming queue receiving all posted tasks.
+  scoped_refptr<IncomingTaskQueue> incoming_queue_;
 
- private:
-  // Allow the MessageLoop to create a MessageLoopProxyImpl.
-  friend class MessageLoop;
-  friend class DeleteHelper<MessageLoopProxyImpl>;
-
-  MessageLoopProxyImpl();
-
-  // Called directly by MessageLoop::~MessageLoop.
-  virtual void WillDestroyCurrentMessageLoop();
-
-
-  bool PostTaskHelper(const tracked_objects::Location& from_here,
-                      const base::Closure& task,
-                      base::TimeDelta delay,
-                      bool nestable);
-
-  // The lock that protects access to target_message_loop_.
-  mutable base::Lock message_loop_lock_;
-  MessageLoop* target_message_loop_;
+  // ID of the thread |this| was created on.
+  PlatformThreadId valid_thread_id_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageLoopProxyImpl);
 };
 
+}  // namespace internal
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_LOOP_PROXY_IMPL_H_