Revert of Remove SkThread.h, include SkMutex.h or SkAtomics.h as appropriate.

src/core/SkMessageBus.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkMessageBus_DEFINED
 #define SkMessageBus_DEFINED
 
 #include "SkLazyPtr.h"
-#include "SkMutex.h"
 #include "SkTArray.h"
 #include "SkTDArray.h"
+#include "SkThread.h"
 #include "SkTypes.h"
 
 template <typename Message>
 class SkMessageBus : SkNoncopyable {
 public:
     // Post a message to be received by all Inboxes for this Message type.  Threadsafe.
     static void Post(const Message& m);
 
     class Inbox {
     public:
@@ skipping 77 matching lines @@
 template <typename Message>
 /*static*/ void SkMessageBus<Message>::Post(const Message& m) {
     SkMessageBus<Message>* bus = SkMessageBus<Message>::Get();
     SkAutoMutexAcquire lock(bus->fInboxesMutex);
     for (int i = 0; i < bus->fInboxes.count(); i++) {
         bus->fInboxes[i]->receive(m);
     }
 }
 
 #endif  // SkMessageBus_DEFINED