Delete dead code. SkBitmapHasher has not been used since gm.

src/utils/SkBitmapHasher.h

-
-/*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#ifndef SkBitmapHasher_DEFINED
-#define SkBitmapHasher_DEFINED
-
-#include "SkBitmap.h"
-
-/**
- * Static class that generates a uint64 hash digest from an SkBitmap.
- */
-class SkBitmapHasher {
-public:
-    /**
-     * Fills in "result" with a hash of the pixels in this bitmap.
-     *
-     * If this is unable to compute the hash for some reason,
-     * it returns false.
-     *
-     * Note: depending on the bitmap colortype, we may need to create an
-     * intermediate SkBitmap and copy the pixels over to it... so in some
-     * cases, performance and memory usage can suffer.
-     */
-    static bool ComputeDigest(const SkBitmap& bitmap, uint64_t *result);
-
-private:
-    static bool ComputeDigestInternal(const SkBitmap& bitmap, uint64_t *result);
-};
-
-#endif