Rewrite GrTextureMaker to disentangle bitmap case from base class and give GPU object a say in what…

include/gpu/SkGr.h

Index: include/gpu/SkGr.h
diff --git a/include/gpu/SkGr.h b/include/gpu/SkGr.h
index 591d3d88a437987cd1cb82b6b8bfbd4125e0d9f0..17625c4e4eb42679f9923c3256082b81ccb3a653 100644
--- a/include/gpu/SkGr.h
+++ b/include/gpu/SkGr.h
@@ -65,9 +65,11 @@ static inline GrColor SkPMColorToGrColor(SkPMColor c) {
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-
+/** Returns a texture representing the bitmap that is compatible with the GrTextureParams. The
+    texture is inserted into the cache (unless the bitmap is marked volatile) and can be
+    retrieved again via this function. */
 GrTexture* GrRefCachedBitmapTexture(GrContext*, const SkBitmap&, const GrTextureParams&);
-    
+
 // TODO: Move SkImageInfo2GrPixelConfig to SkGrPriv.h (requires cleanup to SkWindow its subclasses).
 GrPixelConfig SkImageInfo2GrPixelConfig(SkColorType, SkAlphaType, SkColorProfileType);