Drop AndroidCodecSrc::kDivisor_Mode

This is redundant with BRD tests.

BUG=skia:5307
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1976303002

Review-Url: https://codereview.chromium.org/1976303002
diff --git a/dm/DMSrcSink.h b/dm/DMSrcSink.h
index 5a734a6..b486642 100644
--- a/dm/DMSrcSink.h
+++ b/dm/DMSrcSink.h
@@ -137,14 +137,7 @@
 
 class AndroidCodecSrc : public Src {
 public:
-    enum Mode {
-        kFullImage_Mode,
-        // Splits the image into multiple subsets using a divisor and decodes the subsets
-        // separately.
-        kDivisor_Mode,
-    };
-
-    AndroidCodecSrc(Path, Mode, CodecSrc::DstColorType, SkAlphaType, int sampleSize);
+    AndroidCodecSrc(Path, CodecSrc::DstColorType, SkAlphaType, int sampleSize);
 
     Error draw(SkCanvas*) const override;
     SkISize size() const override;
@@ -153,7 +146,6 @@
     bool serial() const override { return fRunSerially; }
 private:
     Path                    fPath;
-    Mode                    fMode;
     CodecSrc::DstColorType  fDstColorType;
     SkAlphaType             fDstAlphaType;
     int                     fSampleSize;