start to remove lockPixels from bitmapshader

include/core/SkPixelRef.h

Index: include/core/SkPixelRef.h
diff --git a/include/core/SkPixelRef.h b/include/core/SkPixelRef.h
index 0487e426109a2e84381e84aff4638ec0c6eccfb3..64e08765bed8a3c1e1b9f3f1a652e9959b0a1865 100644
--- a/include/core/SkPixelRef.h
+++ b/include/core/SkPixelRef.h
@@ -141,6 +141,37 @@ public:
         return this->onRefEncodedData();
     }
 
+    /**
+     *  Experimental -- tells the caller if it is worth it to call decodeInto().
+     *  Just an optimization at this point, to avoid checking the cache first.
+     *  We may remove/change this call in the future.
+     */
+    bool implementsDecodeInto() {
+        return this->onImplementsDecodeInto();
+    }
+
+    /**
+     *  Return a decoded instance of this pixelRef in bitmap. If this cannot be
+     *  done, return false and the bitmap parameter is ignored/unchanged.
+     *
+     *  pow2 is the requeste power-of-two downscale that the caller needs. This
+     *  can be ignored, and the "original" size can be returned, but if the
+     *  underlying codec can efficiently return a smaller size, that should be
+     *  done. Some examples:
+     *
+     *  To request the "base" version (original scale), pass 0 for pow2
+     *  To request 1/2 scale version (1/2 width, 1/2 height), pass 1 for pow2
+     *  To request 1/4 scale version (1/4 width, 1/4 height), pass 2 for pow2
+     *  ...
+     *
+     *  If this returns true, then bitmap must be "locked" such that
+     *  bitmap->getPixels() will return the correct address.
+     */
+    bool decodeInto(int pow2, SkBitmap* bitmap) {
+        SkASSERT(pow2 >= 0);
+        return this->onDecodeInto(pow2, bitmap);
+    }
+
     /** Are we really wrapping a texture instead of a bitmap?
      */
     virtual GrTexture* getTexture() { return NULL; }
@@ -190,6 +221,11 @@ protected:
     /** Default impl returns true */
     virtual bool onLockPixelsAreWritable() const;
 
+    // returns false;
+    virtual bool onImplementsDecodeInto();
+    // returns false;
+    virtual bool onDecodeInto(int pow2, SkBitmap* bitmap);
+
     /**
      *  For pixelrefs that don't have access to their raw pixels, they may be
      *  able to make a copy of them (e.g. if the pixels are on the GPU).