add applyFilter() to SkImage

src/image/SkImage_Gpu.h

Index: src/image/SkImage_Gpu.h
diff --git a/src/image/SkImage_Gpu.h b/src/image/SkImage_Gpu.h
index 8bfdfa7cd834e2fed6260f2dc64cb4f12d5fb952..7913c5c82a513a992eac3133622528f822369de9 100644
--- a/src/image/SkImage_Gpu.h
+++ b/src/image/SkImage_Gpu.h
@@ -43,6 +43,12 @@ public:
     bool isOpaque() const override;
     bool onReadPixels(const SkImageInfo&, void* dstPixels, size_t dstRowBytes,
                       int srcX, int srcY) const override;
+    SkImage* onApplyFilter(SkImageFilter*, SkIPoint* offset,
+                           bool forceResultToOriginalSize) const override;
+
+    SkSurface* onNewSurface(const SkImageInfo& info) const override {
+        return SkSurface::NewRenderTarget(fTexture->getContext(), SkSurface::kNo_Budgeted, info);
+    }
 
 private:
     SkAutoTUnref<GrTexture>     fTexture;