Add alphaType() to SkImage

src/image/SkImage_Raster.cpp

Index: src/image/SkImage_Raster.cpp
diff --git a/src/image/SkImage_Raster.cpp b/src/image/SkImage_Raster.cpp
index abdecb9794e077ce0ad2d7391860c00f037e8da6..358e91a0fa75473f5e6a65153cadefacb10096d5 100644
--- a/src/image/SkImage_Raster.cpp
+++ b/src/image/SkImage_Raster.cpp
@@ -78,6 +78,9 @@ public:
     SkImageInfo onImageInfo() const override {
         return fBitmap.info();
     }
+    SkAlphaType onAlphaType() const override {
+        return fBitmap.alphaType();
+    }
 
     bool onReadPixels(const SkImageInfo&, void*, size_t, int srcX, int srcY, CachingHint) const override;
     bool onPeekPixels(SkPixmap*) const override;
@@ -94,7 +97,6 @@ public:
 
     SkPixelRef* getPixelRef() const { return fBitmap.pixelRef(); }
 
-    bool isOpaque() const override;
     bool onAsLegacyBitmap(SkBitmap*, LegacyBitmapMode) const override;
 
     SkImage_Raster(const SkBitmap& bm, bool bitmapMayBeMutable = false)
@@ -360,10 +362,6 @@ const SkPixelRef* SkBitmapImageGetPixelRef(const SkImage* image) {
     return ((const SkImage_Raster*)image)->getPixelRef();
 }
 
-bool SkImage_Raster::isOpaque() const {
-    return fBitmap.isOpaque();
-}
-
 bool SkImage_Raster::onAsLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode mode) const {
     if (kRO_LegacyBitmapMode == mode) {
         // When we're a snapshot from a surface, our bitmap may not be marked immutable