Made MessagePump a non-thread safe class.

base/message_loop/message_loop_proxy_impl.cc

Index: base/message_loop/message_loop_proxy_impl.cc
diff --git a/base/message_loop/message_loop_proxy_impl.cc b/base/message_loop/message_loop_proxy_impl.cc
index 7dc8caa9f4c047f93cf7366c2e373ad1eebdd0fb..38cc10426604d2ec1ca2c7d63cdd83840bec69c7 100644
--- a/base/message_loop/message_loop_proxy_impl.cc
+++ b/base/message_loop/message_loop_proxy_impl.cc
@@ -16,14 +16,16 @@ 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 {
@@ -66,18 +68,40 @@ 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;
 }