Add AutoThread types for Windows that initialize COM.

remoting/base/auto_thread.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_BASE_AUTO_THREAD_H_
 #define REMOTING_BASE_AUTO_THREAD_H_
 
 #include <string>
 
 #include "base/message_loop.h"
@@ skipping 11 matching lines @@
 // All pending tasks queued on the thread's message loop will run to completion
 // before the thread is terminated.
 //
 // After the thread is stopped, the destruction sequence is:
 //
 //  (1) Thread::CleanUp()
 //  (2) MessageLoop::~MessageLoop
 //  (3.b)    MessageLoop::DestructionObserver::WillDestroyCurrentMessageLoop
 class AutoThread : base::PlatformThread::Delegate {
  public:
+  // Used to specify the type of MessageLoop to create on the new thread.
+  // On Windows the thread may be intialized for single or multi-threaded COM.
+  enum Type {

[Sergey Ulanov, 2012/11/16 19:23:33]

Do we really need this type? Maybe better to add init_com_with_mta() so that the
API is the same as in base::Thread?

[Wez, 2012/11/16 19:54:54]

This class is already different enough from base::Thread that I don't think
that's a concern here. But Alex seems to agree; see below. :-/

+    TYPE_DEFAULT,
+    TYPE_IO,
+    TYPE_UI,
+#if defined(OS_WIN)
+    TYPE_UI_COM_STA,
+    TYPE_UI_COM_MTA

[alexeypa (please no reviews), 2012/11/16 18:16:09]

MTA does not need a message pump AFAIR. It is not correct to bind MTA to a UI
message loop. How about providing a mechanism to pass a factory/callback that
will instantiate a scoped object on the thread?

In the worst case I think the approach used in base::Thread is better.

[Wez, 2012/11/16 19:54:54]

Quite right; fixed.
OK; I'd just hoped to avoid the extra API the base::Thread approach requires.

+#endif
+  };
+
   // Create an AutoThread with the specified message-loop |type| and |name|.
   // The supplied AutoThreadTaskRunner will be used to join and delete the
   // new thread when no references to it remain.
   static scoped_refptr<AutoThreadTaskRunner> CreateWithType(

[alexeypa (please no reviews), 2012/11/16 18:16:09]

Add a variant CreateWithTypeAndInitializeCom?

[Wez, 2012/11/16 19:54:54]

If I switch the interface to the ugly init_com_with_mta() approach then yes,
I'll add a variant creator function as well.

       const char* name,
       scoped_refptr<AutoThreadTaskRunner> joiner,
-      MessageLoop::Type type);
+      Type type);
   static scoped_refptr<AutoThreadTaskRunner> Create(
       const char* name,
       scoped_refptr<AutoThreadTaskRunner> joiner);
 
   // Construct the AutoThread.  |name| identifies the thread for debugging.
   explicit AutoThread(const char* name);
 
   // Waits for the thread to exit, and then destroys it.
   virtual ~AutoThread();
 
   // Starts a the thread, running the specified type of MessageLoop.  Returns
   // an AutoThreadTaskRunner through which tasks may be posted to the thread
   // if successful, or NULL on failure.
   //
   // Note: This function can't be called on Windows with the loader lock held;
   // i.e. during a DllMain, global object construction or destruction, atexit()
   // callback.
   //
   // NOTE: You must not call this MessageLoop's Quit method directly.  The
   // thread will exit when no references to the TaskRunner remain.
-  scoped_refptr<AutoThreadTaskRunner> StartWithType(MessageLoop::Type type);
+  scoped_refptr<AutoThreadTaskRunner> StartWithType(Type type);
 
   // Shorthand for StartWithType(MessageLoop::TYPE_DEFAULT).
   scoped_refptr<AutoThreadTaskRunner> Start();
 
  private:
   AutoThread(const char* name, AutoThreadTaskRunner* joiner);
 
   void QuitThread(scoped_refptr<base::SingleThreadTaskRunner> task_runner);
   void JoinAndDeleteThread();
 
@@ skipping 16 matching lines @@
 
   // AutoThreadTaskRunner to post a task to to join & delete this thread.
   scoped_refptr<AutoThreadTaskRunner> joiner_;
 
   DISALLOW_COPY_AND_ASSIGN(AutoThread);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_AUTO_THREAD_H_