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

src/utils/SkBitmapHasher.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 "SkBitmap.h"
-#include "SkBitmapHasher.h"
-#include "SkEndian.h"
-#include "SkImageEncoder.h"
-
-#include "SkMD5.h"
-
-/**
- * Write an int32 value to a stream in little-endian order.
- */
-static void write_int32_to_buffer(uint32_t val, SkWStream* out) {
-    val = SkEndian_SwapLE32(val);
-    for (size_t byte = 0; byte < 4; ++byte) {
-        out->write8((uint8_t)(val & 0xff));
-        val = val >> 8;
-    }
-}
-
-/**
- * Return the first 8 bytes of a bytearray, encoded as a little-endian uint64.
- */
-static inline uint64_t first_8_bytes_as_uint64(const uint8_t *bytearray) {
-    return SkEndian_SwapLE64(*(reinterpret_cast<const uint64_t *>(bytearray)));
-}
-
-/*static*/ bool SkBitmapHasher::ComputeDigestInternal(const SkBitmap& bitmap, uint64_t *result) {
-    SkMD5 out;
-
-    // start with the x/y dimensions
-    write_int32_to_buffer(SkToU32(bitmap.width()), &out);
-    write_int32_to_buffer(SkToU32(bitmap.height()), &out);
-
-    // add all the pixel data
-    SkAutoTDelete<SkImageEncoder> enc(CreateARGBImageEncoder());
-    if (!enc->encodeStream(&out, bitmap, SkImageEncoder::kDefaultQuality)) {
-        return false;
-    }
-
-    SkMD5::Digest digest;
-    out.finish(digest);
-    *result = first_8_bytes_as_uint64(digest.data);
-    return true;
-}
-
-/*static*/ bool SkBitmapHasher::ComputeDigest(const SkBitmap& bitmap, uint64_t *result) {
-    if (ComputeDigestInternal(bitmap, result)) {
-        return true;
-    }
-
-    // Hmm, that didn't work. Maybe if we create a new
-    // version of the bitmap it will work better?
-    SkBitmap copyBitmap;
-    if (!bitmap.copyTo(&copyBitmap, kN32_SkColorType)) {
-        return false;
-    }
-    return ComputeDigestInternal(copyBitmap, result);
-}