sRGB support in Ganesh. Several pieces:

src/image/SkImage_Gpu.cpp

Index: src/image/SkImage_Gpu.cpp
diff --git a/src/image/SkImage_Gpu.cpp b/src/image/SkImage_Gpu.cpp
index 79fe72b09ec9ab46872eaf4aaa7b4e2b7b53187e..7a99dfeaa5d1187135c021c6679e35968b821870 100644
--- a/src/image/SkImage_Gpu.cpp
+++ b/src/image/SkImage_Gpu.cpp
@@ -111,7 +111,8 @@ static void apply_premul(const SkImageInfo& info, void* pixels, size_t rowBytes)
 bool SkImage_Gpu::onReadPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                                int srcX, int srcY, CachingHint) const {
     GrPixelConfig config = SkImageInfo2GrPixelConfig(info.colorType(), info.alphaType(),
-                                                     info.profileType());
+                                                     info.profileType(),
+                                                     *fTexture->getContext()->caps());
     uint32_t flags = 0;
     if (kUnpremul_SkAlphaType == info.alphaType() && kPremul_SkAlphaType == fAlphaType) {
         // let the GPU perform this transformation for us