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

tests/PathOpsExtendedTest.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "PathOpsExtendedTest.h"
 #include "PathOpsThreadedCommon.h"
 #include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkForceLinking.h"
 #include "SkMatrix.h"
-#include "SkMutex.h"
 #include "SkPaint.h"
 #include "SkRTConf.h"
 #include "SkStream.h"
+#include "SkThread.h"
 
 #ifdef SK_BUILD_FOR_MAC
 #include <sys/sysctl.h>
 #endif
 
 __SK_FORCE_IMAGE_DECODER_LINKING;
 
 DEFINE_bool2(runFail, f, false, "run tests known to fail.");
 DEFINE_bool2(runBinary, f, false, "run tests known to fail binary sect.");
 
@@ skipping 641 matching lines @@
         if (foundSkip && tests[index].fun != firstTest) {
             SkDebugf("    %s,\n", tests[index].str);
         }
         if (tests[index].fun == stopTest || index == last) {
             break;
         }
         index += reverse ? -1 : 1;
     } while (true);
 #endif
 }