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

dm/DM.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "CrashHandler.h"
 #include "DMJsonWriter.h"
 #include "DMSrcSink.h"
 #include "DMSrcSinkAndroid.h"
 #include "OverwriteLine.h"
 #include "ProcStats.h"
 #include "SkBBHFactory.h"
 #include "SkChecksum.h"
 #include "SkCommonFlags.h"
 #include "SkFontMgr.h"
 #include "SkForceLinking.h"
 #include "SkGraphics.h"
 #include "SkMD5.h"
-#include "SkMutex.h"
 #include "SkOSFile.h"
 #include "SkTHash.h"
 #include "SkTaskGroup.h"
 #include "SkThreadUtils.h"
 #include "Test.h"
 #include "Timer.h"
 #include "sk_tool_utils.h"
 
 DEFINE_string(src, "tests gm skp image", "Source types to test.");
 DEFINE_bool(nameByHash, false,
@@ skipping 779 matching lines @@
     }
     return 0;
 }
 
 #if !defined(SK_BUILD_FOR_IOS)
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     return dm_main();
 }
 #endif