remove unused SkPixelRef constructor

TBR=

Author: reed@google.com

Review URL: https://codereview.chromium.org/390893002

include/core/SkPixelRef.h

@@ -320,9 +320,6 @@ protected:
     */
     SkBaseMutex* mutex() const { return fMutex; }
 
-    // serialization
-    SkPixelRef(SkReadBuffer&, SkBaseMutex*);
-
     // 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).

src/core/SkPixelRef.cpp

@@ -1,13 +1,11 @@
-
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
+
 #include "SkPixelRef.h"
-#include "SkReadBuffer.h"
-#include "SkWriteBuffer.h"
 #include "SkThread.h"
 
 #ifdef SK_USE_POSIX_THREADS