Add the method isOpaque() 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 464a4ba7a4177829d0382d89c05f97c6ace3ee5a..9860957f1e0fcf87dbf239e03ecb67038f8d3126 100644
--- a/src/image/SkImage_Raster.cpp
+++ b/src/image/SkImage_Raster.cpp
@@ -66,6 +66,8 @@ public:
 
     virtual SkShader* onNewShader(SkShader::TileMode, SkShader::TileMode) const SK_OVERRIDE;
 
+    virtual bool isOpaque() const SK_OVERRIDE;
+
 private:
     SkImage_Raster() : INHERITED(0, 0) {}
 
@@ -203,3 +205,7 @@ SkImage* SkNewImageFromPixelRef(const SkImageInfo& info, SkPixelRef* pr,
 SkPixelRef* SkBitmapImageGetPixelRef(SkImage* image) {
     return ((SkImage_Raster*)image)->getPixelRef();
 }
+
+bool SkImage_Raster::isOpaque() const {
+    return fBitmap.isOpaque();
+}