Adds read pixels to GrTexture and GrRenderTarget
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
diff --git a/gpu/src/GrGpuGLFixed.cpp b/gpu/src/GrGpuGLFixed.cpp
index 3e6d909..446949f 100644
--- a/gpu/src/GrGpuGLFixed.cpp
+++ b/gpu/src/GrGpuGLFixed.cpp
@@ -192,7 +192,7 @@
             GrGLTexture* texture = (GrGLTexture*)fCurrDrawState.fTextures[s];
             if (NULL != texture) {
                 TextureEnvRGBOperands nextRGBOperand0 =
-                    (texture->config() == GrTexture::kAlpha_8_PixelConfig) ?
+                    (GrPixelConfigIsAlphaOnly(texture->config())) ?
                         kAlpha_TextureEnvRGBOperand :
                         kColor_TextureEnvRGBOperand;
                 if (fHWRGBOperand0[s] != nextRGBOperand0) {