Make MessageLoopProxy::current() usable on threads that don't have MessageLoop.

base/message_loop.cc

 // 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.
 
 #include "base/message_loop.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 121 matching lines @@
       message_histogram_(NULL),
       state_(NULL),
 #ifdef OS_WIN
       os_modal_loop_(false),
 #endif  // OS_WIN
       next_sequence_num_(0) {
   DCHECK(!current()) << "should only have one message loop per thread";
   lazy_tls_ptr.Pointer()->Set(this);
 
   message_loop_proxy_ = new base::MessageLoopProxyImpl();
+  base::SingleThreadTaskRunner::SetCurrent(message_loop_proxy_);
 
 // TODO(rvargas): Get rid of the OS guards.
 #if defined(OS_WIN)
 #define MESSAGE_PUMP_UI new base::MessagePumpForUI()
 #define MESSAGE_PUMP_IO new base::MessagePumpForIO()
 #elif defined(OS_MACOSX)
 #define MESSAGE_PUMP_UI base::MessagePumpMac::Create()
 #define MESSAGE_PUMP_IO new base::MessagePumpLibevent()
 #elif defined(OS_NACL)
 // Currently NaCl doesn't have a UI or an IO MessageLoop.
@@ skipping 40 matching lines @@
     if (!did_work)
       break;
   }
   DCHECK(!did_work);
 
   // Let interested parties have one last shot at accessing this.
   FOR_EACH_OBSERVER(DestructionObserver, destruction_observers_,
                     WillDestroyCurrentMessageLoop());
 
   // Tell the message_loop_proxy that we are dying.
+  base::SingleThreadTaskRunner::SetCurrent(NULL);
   static_cast<base::MessageLoopProxyImpl*>(message_loop_proxy_.get())->
       WillDestroyCurrentMessageLoop();
   message_loop_proxy_ = NULL;
 
   // OK, now make it so that no one can find us.
   lazy_tls_ptr.Pointer()->Set(NULL);
 
 #if defined(OS_WIN)
   // If we left the high-resolution timer activated, deactivate it now.
   // Doing this is not-critical, it is mainly to make sure we track
@@ skipping 582 matching lines @@
                                            Watcher *delegate) {
   return pump_libevent()->WatchFileDescriptor(
       fd,
       persistent,
       static_cast<base::MessagePumpLibevent::Mode>(mode),
       controller,
       delegate);
 }
 
 #endif