implement isABitmap for imageshader, return localmatrix for bitmap's impl

src/image/SkImage_Base.h

Index: src/image/SkImage_Base.h
diff --git a/src/image/SkImage_Base.h b/src/image/SkImage_Base.h
index f1b902bd84118b2c0fc646c60ed68a6ed7f9dcb1..1cfb7daad67e126b792e4bd500dc497a9314dc85 100644
--- a/src/image/SkImage_Base.h
+++ b/src/image/SkImage_Base.h
@@ -33,6 +33,8 @@ public:
 
     virtual bool onPeekPixels(SkPixmap*) const { return false; }
 
+    virtual const SkBitmap* onPeekBitmap() const { return nullptr; }
+
     // Default impl calls onDraw
     virtual bool onReadPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
                               int srcX, int srcY, CachingHint) const;