Made MessagePump a non-thread safe class.

base/message_loop/message_loop_proxy_impl.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 "base/message_loop/message_loop_proxy_impl.h"
 
 #include "base/location.h"
 #include "base/threading/thread_restrictions.h"
 
 namespace base {
 
 MessageLoopProxyImpl::~MessageLoopProxyImpl() {
 }
 
 bool MessageLoopProxyImpl::PostDelayedTask(
     const tracked_objects::Location& from_here,
     const base::Closure& task,
     base::TimeDelta delay) {
-  return PostTaskHelper(from_here, task, delay, true);
+  DCHECK(!task.is_null()) << from_here.ToString();
+  return AddToIncomingQueue(from_here, task, delay, true);
 }
 
 bool MessageLoopProxyImpl::PostNonNestableDelayedTask(
     const tracked_objects::Location& from_here,
     const base::Closure& task,
     base::TimeDelta delay) {
-  return PostTaskHelper(from_here, task, delay, false);
+  DCHECK(!task.is_null()) << from_here.ToString();
+  return AddToIncomingQueue(from_here, task, delay, false);
 }
 
 bool MessageLoopProxyImpl::RunsTasksOnCurrentThread() const {
   // We shouldn't use MessageLoop::current() since it uses LazyInstance which
   // may be deleted by ~AtExitManager when a WorkerPool thread calls this
   // function.
   // http://crbug.com/63678
   base::ThreadRestrictions::ScopedAllowSingleton allow_singleton;
   AutoLock lock(message_loop_lock_);
   return (target_message_loop_ &&
@@ skipping 22 matching lines @@
     }
   }
   if (!delete_later)
     delete this;
 }
 
 MessageLoopProxyImpl::MessageLoopProxyImpl()
     : target_message_loop_(MessageLoop::current()) {
 }
 
-bool MessageLoopProxyImpl::PostTaskHelper(
-    const tracked_objects::Location& from_here, const base::Closure& task,
-    base::TimeDelta delay, bool nestable) {
-  AutoLock lock(message_loop_lock_);
-  if (target_message_loop_) {
-    if (nestable) {
-      target_message_loop_->PostDelayedTask(from_here, task, delay);
-    } else {
-      target_message_loop_->PostNonNestableDelayedTask(from_here, task, delay);
+bool MessageLoopProxyImpl::AddToIncomingQueue(
+    const tracked_objects::Location& from_here,
+    const Closure& task,
+    TimeDelta delay,
+    bool nestable) {
+  AutoLock locked(message_loop_lock_);
+  if (!target_message_loop_) {
+    // Reset |task|.
+    Closure reset_task = task;
+    return false;
+  }
+
+  target_message_loop_->AddToIncomingQueue(from_here, task, delay, nestable);
+  return true;
+}
+
+bool MessageLoopProxyImpl::TryAddToIncomingQueue(
+    const tracked_objects::Location& from_here,
+    const Closure& task) {
+  if (message_loop_lock_.Try()) {
+    AutoLock locked(message_loop_lock_, AutoLock::AlreadyAcquired());
+    if (!target_message_loop_) {
+      // Reset |task|.
+      Closure reset_task = task;
+      return false;
     }
+
+    target_message_loop_->AddToIncomingQueue(from_here, task, TimeDelta(),
+                                             true);
     return true;
   }
+
+  // Reset |task|.
+  Closure reset_task = task;
   return false;
 }
 
 scoped_refptr<MessageLoopProxy>
 MessageLoopProxy::current() {
   MessageLoop* cur_loop = MessageLoop::current();
   if (!cur_loop)
     return NULL;
   return cur_loop->message_loop_proxy();
 }
 
 }  // namespace base