Add MessageLoop::AssertIdle(). Use in ChromeOS audio threads.

base/message_loop.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_MESSAGE_LOOP_H_
 #define BASE_MESSAGE_LOOP_H_
 #pragma once
 
 #include <queue>
 #include <string>
@@ skipping 297 matching lines @@
     return !high_resolution_timer_expiration_.is_null();
 #else
     return true;
 #endif
   }
 
   // When we go into high resolution timer mode, we will stay in hi-res mode
   // for at least 1s.
   static const int kHighResolutionTimerModeLeaseTimeMs = 1000;
 
+  // Asserts that the MessageLoop is "idle". in reality, we only check
+  // |incoming_queue_|, since we don't want to lock |work_queue_|.
+  void AssertIdle() const;
+
   //----------------------------------------------------------------------------
  protected:
   struct RunState {
     // Used to count how many Run() invocations are on the stack.
     int run_depth;
 
     // Used to record that Quit() was called, or that we should quit the pump
     // once it becomes idle.
     bool quit_received;
 
@@ skipping 126 matching lines @@
   // insider a (accidentally induced?) nested message pump.
   bool nestable_tasks_allowed_;
 
   bool exception_restoration_;
 
   std::string thread_name_;
   // A profiling histogram showing the counts of various messages and events.
   scoped_refptr<base::Histogram> message_histogram_;
 
   // A null terminated list which creates an incoming_queue of tasks that are
-  // aquired under a mutex for processing on this instance's thread. These tasks
+  // acquired under a mutex for processing on this instance's thread. These tasks
   // have not yet been sorted out into items for our work_queue_ vs items that
   // will be handled by the TimerManager.
   TaskQueue incoming_queue_;
   // Protect access to incoming_queue_.
-  base::Lock incoming_queue_lock_;
+  mutable base::Lock incoming_queue_lock_;
 
   RunState* state_;
 
 #if defined(OS_WIN)
   base::TimeTicks high_resolution_timer_expiration_;
 #endif
 
   // The next sequence number to use for delayed tasks.
   int next_sequence_num_;
 
@@ skipping 117 matching lines @@
 #endif  // defined(OS_POSIX)
 };
 
 // Do not add any member variables to MessageLoopForIO!  This is important b/c
 // MessageLoopForIO is often allocated via MessageLoop(TYPE_IO).  Any extra
 // data that you need should be stored on the MessageLoop's pump_ instance.
 COMPILE_ASSERT(sizeof(MessageLoop) == sizeof(MessageLoopForIO),
                MessageLoopForIO_should_not_have_extra_member_variables);
 
 #endif  // BASE_MESSAGE_LOOP_H_