Skia side RGB to YUV gpu conversion

include/core/SkImageDecoder.h

Index: include/core/SkImageDecoder.h
diff --git a/include/core/SkImageDecoder.h b/include/core/SkImageDecoder.h
index b258afedce184e79f3907c7cf8f29a6318c068ba..c2aa18f7d897371884eb356bdc39ea48fc13e328 100644
--- a/include/core/SkImageDecoder.h
+++ b/include/core/SkImageDecoder.h
@@ -46,6 +46,17 @@ public:
     */
     virtual Format getFormat() const;
 
+
+    /**  Returns the sizes of each component of the image
+    */
+    virtual bool getImageFormat(SkStream*, SkISize sizes[3]) {

[scroggo, 2014/07/18 21:52:40]

This name doesn't seem to match what it does. A better name might be
getComponentSizes?

+        return false;
+    }
+
+    /* If the decoder wants to support YUV based decoding, this method must be overridden.
+    */
+    virtual void setYUVBuffers(void* yuv[3], size_t rowBytes[3]) {}

[scroggo, 2014/07/18 21:52:40]

For both of these, why not have two functions:

void setYUVBuffers(...) {
  this->onSetYUVBuffers(...);
}

virtual void onSetYUVBuffers(...) {}

Then we've separated the interface from the implementation (we mostly follow
this convention in Skia).

+
     /** Return the format of the SkStreamRewindable or kUnknown_Format if it cannot be determined.
         Rewinds the stream before returning.
     */