This means we have to be even more cautious about when we call lock, and we should
always check getTexture() first if we can handle a texture directly, rather than
forcing the read-back to get the bits.
git-svn-id: http://skia.googlecode.com/svn/trunk@1815 2bbb7eff-a529-9590-31e7-b0007b416f81
Adds SkGrRenderTargetPixelRef for SkBitmaps that are backed by RTs that aren't textures.
Adds onReadPixels implementations for SkGr pixel ref types
git-svn-id: http://skia.googlecode.com/svn/trunk@1056 2bbb7eff-a529-9590-31e7-b0007b416f81
