Adding TryPostTask to the message loop

base/synchronization/lock.h

 // 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.
 
 #ifndef BASE_SYNCHRONIZATION_LOCK_H_
 #define BASE_SYNCHRONIZATION_LOCK_H_
 
 #include "base/base_export.h"
 #include "base/synchronization/lock_impl.h"
 #include "base/threading/platform_thread.h"
@@ skipping 78 matching lines @@
 
   // Platform specific underlying lock implementation.
   internal::LockImpl lock_;
 
   DISALLOW_COPY_AND_ASSIGN(Lock);
 };
 
 // A helper class that acquires the given Lock while the AutoLock is in scope.
 class AutoLock {
  public:
+  struct AlreadyAcquired {};
+
   explicit AutoLock(Lock& lock) : lock_(lock) {
     lock_.Acquire();
   }
 
+  AutoLock(Lock& lock, const AlreadyAcquired&) : lock_(lock) {
+    lock_.AssertAcquired();
+  }
+
   ~AutoLock() {
     lock_.AssertAcquired();
     lock_.Release();
   }
 
  private:
   Lock& lock_;
   DISALLOW_COPY_AND_ASSIGN(AutoLock);
 };
 
@@ skipping 12 matching lines @@
   }
 
  private:
   Lock& lock_;
   DISALLOW_COPY_AND_ASSIGN(AutoUnlock);
 };
 
 }  // namespace base
 
 #endif  // BASE_SYNCHRONIZATION_LOCK_H_