Revert of Modernize SkMutex and SkSemaphore.

include/core/SkPixelRef.h

 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkPixelRef_DEFINED
 #define SkPixelRef_DEFINED
 
@@ skipping 324 matching lines @@
      */
     virtual size_t getAllocatedSizeInBytes() const;
 
     virtual bool onRequestLock(const LockRequest&, LockResult*);
 
     virtual bool onIsLazyGenerated() const { return false; }
 
     /** Return the mutex associated with this pixelref. This value is assigned
         in the constructor, and cannot change during the lifetime of the object.
     */
-    SkMutex* mutex() const { return &fMutex; }
+    SkBaseMutex* mutex() const { return &fMutex; }
 
     // only call from constructor. Flags this to always be locked, removing
     // the need to grab the mutex and call onLockPixels/onUnlockPixels.
     // Performance tweak to avoid those calls (esp. in multi-thread use case).
     void setPreLocked(void*, size_t rowBytes, SkColorTable*);
 
 private:
     mutable SkMutex fMutex;
 
     // mostly const. fInfo.fAlpahType can be changed at runtime.
@@ skipping 58 matching lines @@
     /**
      *  Allocate a new pixelref matching the specified ImageInfo, allocating
      *  the memory for the pixels. If the ImageInfo requires a ColorTable,
      *  the pixelref will ref() the colortable.
      *  On failure return NULL.
      */
     virtual SkPixelRef* create(const SkImageInfo&, size_t rowBytes, SkColorTable*) = 0;
 };
 
 #endif