Add file thread in MessageHostContext.

remoting/host/chromoting_host_context.h

 // 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.
 
 #ifndef REMOTING_HOST_CHROMOTING_HOST_CONTEXT_H_
 #define REMOTING_HOST_CHROMOTING_HOST_CONTEXT_H_
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread.h"
 #include "remoting/jingle_glue/jingle_thread.h"
 
 namespace remoting {
 
 // A class that manages threads and running context for the chromoting host
 // process.  This class is virtual only for testing purposes (see below).
 class ChromotingHostContext {
  public:
   // Create a context.
-  ChromotingHostContext(base::MessageLoopProxy* io_message_loop,
-                        base::MessageLoopProxy* ui_message_loop);
+  ChromotingHostContext(base::MessageLoopProxy* ui_message_loop);
   virtual ~ChromotingHostContext();
 
   // TODO(ajwong): Move the Start method out of this class. Then
   // create a static factory for construction, and destruction.  We
   // should be able to remove the need for virtual functions below
   // with that design, while preserving the relative simplicity of
   // this API.
   virtual bool Start();
 
   virtual JingleThread* jingle_thread();
 
-  virtual base::MessageLoopProxy* io_message_loop();
-  virtual base::MessageLoopProxy* ui_message_loop();
+
   virtual MessageLoop* main_message_loop();
   virtual MessageLoop* encode_message_loop();
   virtual base::MessageLoopProxy* network_message_loop();
   virtual MessageLoop* desktop_message_loop();
+  virtual base::MessageLoopProxy* ui_message_loop();
+  virtual MessageLoop* file_message_loop();
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ChromotingHostContextTest, StartAndStop);
 
   // A thread that hosts all network operations.
   JingleThread jingle_thread_;
 
-  // A thread that hosts ChromotingHost and performs rate control.
+  // TODO(sergeyu): The "main" thread is used just by the
+  // capturer. Consider renaming it.
   base::Thread main_thread_;
 
   // A thread that hosts all encode operations.
   base::Thread encode_thread_;
 
   // A thread that hosts desktop integration (capture, input injection, etc)
   // This is NOT a Chrome-style UI thread.
   base::Thread desktop_thread_;
 
-  scoped_refptr<base::MessageLoopProxy> io_message_loop_;
+  // Thread for blocking IO operations.
+  base::Thread file_thread_;
+
   scoped_refptr<base::MessageLoopProxy> ui_message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromotingHostContext);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_CHROMOTING_HOST_CONTEXT_H_