Adds some CHECKs to MessagePumpMojo

mojo/common/message_pump_mojo.h

 // Copyright 2013 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 MOJO_COMMON_MESSAGE_PUMP_MOJO_H_
 #define MOJO_COMMON_MESSAGE_PUMP_MOJO_H_
 
 #include <map>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 13 matching lines @@
  public:
   MessagePumpMojo();
   virtual ~MessagePumpMojo();
 
   // Static factory function (for using with |base::Thread::Options|, wrapped
   // using |base::Bind()|).
   static scoped_ptr<base::MessagePump> Create();
 
   // Registers a MessagePumpMojoHandler for the specified handle. Only one
   // handler can be registered for a specified handle.
+  // NOTE: a value of 0 for |deadline| indicates an indefinite timeout.
   void AddHandler(MessagePumpMojoHandler* handler,
                   const Handle& handle,
                   MojoHandleSignals wait_signals,
                   base::TimeTicks deadline);
 
   void RemoveHandler(const Handle& handle);
 
   // MessagePump:
   virtual void Run(Delegate* delegate) OVERRIDE;
   virtual void Quit() OVERRIDE;
@@ skipping 54 matching lines @@
   // notify it.
   int next_handler_id_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePumpMojo);
 };
 
 }  // namespace common
 }  // namespace mojo
 
 #endif  // MOJO_COMMON_MESSAGE_PUMP_MOJO_H_