Delete dead BitmapRegionDecoder code in tools

tools/SkBitmapRegionSampler.h

-/*
- * Copyright 2015 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 "SkBitmapRegionDecoder.h"
-#include "SkImageDecoder.h"
-#include "SkTemplates.h"
-
-/*
- * This class aims to duplicate the current implementation of
- * SkBitmapRegionDecoder in Android.
- */
-class SkBitmapRegionSampler : public SkBitmapRegionDecoder {
-public:
-
-    /*
-     * Takes ownership of pointer to decoder
-     */
-    SkBitmapRegionSampler(SkImageDecoder* decoder, int width, int height);
-
-    bool decodeRegion(SkBitmap* bitmap, SkBitmap::Allocator* allocator,
-                      const SkIRect& desiredSubset, int sampleSize,
-                      SkColorType colorType, bool requireUnpremul) override;
-
-    bool conversionSupported(SkColorType colorType) override {
-        // SkBitmapRegionSampler does not allow the client to check if the conversion
-        // is supported.  We will return true as a default.  If the conversion is in
-        // fact not supported, decodeRegion() will ignore the prefColorType and choose
-        // its own color type.  We catch this and fail non-fatally in our test code.
-        return true;
-    }
-
-    SkEncodedFormat getEncodedFormat() override { return (SkEncodedFormat) fDecoder->getFormat(); }
-
-private:
-
-    SkAutoTDelete<SkImageDecoder> fDecoder;
-
-    typedef SkBitmapRegionDecoder INHERITED;
-
-};