Delete SkBitmapRegionCanvas

This was an approach we considered for implementing Android's
BitmapRegionDecoder.

It was useful for testing and comparison, but now is no longer worth
maintaining and testing.

The approach to subset/scaled decodes (clipped decode, then scale)
may be worth reconsidering at some point.

BUG=skia:5307
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1990543002

Review-Url: https://codereview.chromium.org/1990543002
diff --git a/bench/BitmapRegionDecoderBench.h b/bench/BitmapRegionDecoderBench.h
index 7c331ae..69588b2 100644
--- a/bench/BitmapRegionDecoderBench.h
+++ b/bench/BitmapRegionDecoderBench.h
@@ -18,16 +18,13 @@
 /**
  *  Benchmark Android's BitmapRegionDecoder for a particular colorType, sampleSize, and subset.
  *
- *  fStrategy determines which of various implementations is to be used.
- *
  *  nanobench.cpp handles creating benchmarks for interesting scaled subsets.  We strive to test
  *  on real use cases.
  */
 class BitmapRegionDecoderBench : public Benchmark {
 public:
     // Calls encoded->ref()
-    BitmapRegionDecoderBench(const char* basename, SkData* encoded,
-            SkBitmapRegionDecoder::Strategy strategy, SkColorType colorType,
+    BitmapRegionDecoderBench(const char* basename, SkData* encoded, SkColorType colorType,
             uint32_t sampleSize, const SkIRect& subset);
 
 protected:
@@ -40,7 +37,6 @@
     SkString                                       fName;
     SkAutoTDelete<SkBitmapRegionDecoder>           fBRD;
     SkAutoTUnref<SkData>                           fData;
-    const SkBitmapRegionDecoder::Strategy          fStrategy;
     const SkColorType                              fColorType;
     const uint32_t                                 fSampleSize;
     const SkIRect                                  fSubset;