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

src/ports/SkFontHost_FreeType_common.h

 /*
  * Copyright 2006-2012 The Android Open Source Project
  * Copyright 2012 Mozilla Foundation
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SKFONTHOST_FREETYPE_COMMON_H_
 #define SKFONTHOST_FREETYPE_COMMON_H_
 
 #include "SkGlyph.h"
-#include "SkMutex.h"
 #include "SkScalerContext.h"
 #include "SkTypeface.h"
 #include "SkTypes.h"
 
 #include <ft2build.h>
 #include FT_FREETYPE_H
 
 class SkScalerContext_FreeType_Base : public SkScalerContext {
 protected:
     // See http://freetype.sourceforge.net/freetype2/docs/reference/ft2-bitmap_handling.html#FT_Bitmap_Embolden
@@ skipping 61 matching lines @@
     virtual size_t onGetTableData(SkFontTableTag, size_t offset,
                                   size_t length, void* data) const override;
 
 private:
     mutable int fGlyphCount;
 
     typedef SkTypeface INHERITED;
 };
 
 #endif // SKFONTHOST_FREETYPE_COMMON_H_