Preserve color space of images in deferred texture API

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 b769e0a68409d9e6f7678602134a18a643885a5c..af1668193384d398dc140b8980ef0bfb00593867 100644
--- a/src/image/SkImage_Gpu.cpp
+++ b/src/image/SkImage_Gpu.cpp
@@ -492,7 +492,7 @@ size_t SkImage::getDeferredTextureImageData(const GrContextThreadSafeProxy& prox
         if (!data && !this->peekPixels(nullptr)) {
             return 0;
         }
-        info = SkImageInfo::MakeN32(scaledSize.width(), scaledSize.height(), this->alphaType());
+        info = as_IB(this)->onImageInfo().makeWH(scaledSize.width(), scaledSize.height());
         pixelSize = SkAlign8(SkAutoPixmapStorage::AllocSize(info, nullptr));
         if (fillMode) {
             pixmap.alloc(info);
@@ -509,7 +509,6 @@ size_t SkImage::getDeferredTextureImageData(const GrContextThreadSafeProxy& prox
             SkASSERT(!pixmap.ctable());
         }
     }
-    SkAlphaType at = this->isOpaque() ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
     int mipMapLevelCount = 1;
     if (useMipMaps) {
         // SkMipMap only deals with the mipmap levels it generates, which does
@@ -528,7 +527,7 @@ size_t SkImage::getDeferredTextureImageData(const GrContextThreadSafeProxy& prox
              currentMipMapLevelIndex--) {
             SkISize mipSize = SkMipMap::ComputeLevelSize(scaledSize.width(), scaledSize.height(),
                                                          currentMipMapLevelIndex);
-            SkImageInfo mipInfo = SkImageInfo::MakeN32(mipSize.fWidth, mipSize.fHeight, at);
+            SkImageInfo mipInfo = info.makeWH(mipSize.fWidth, mipSize.fHeight);
             pixelSize += SkAlign8(SkAutoPixmapStorage::AllocSize(mipInfo, nullptr));
         }
     }
@@ -614,10 +613,6 @@ size_t SkImage::getDeferredTextureImageData(const GrContextThreadSafeProxy& prox
         // range 0-(x-1).
         for (int generatedMipLevelIndex = 0; generatedMipLevelIndex < mipMapLevelCount - 1;
              generatedMipLevelIndex++) {
-            SkISize mipSize = SkMipMap::ComputeLevelSize(scaledSize.width(), scaledSize.height(),
-                                                         generatedMipLevelIndex);
-
-            SkImageInfo mipInfo = SkImageInfo::MakeN32(mipSize.fWidth, mipSize.fHeight, at);
             SkMipMap::Level mipLevel;
             mipmaps->getLevel(generatedMipLevelIndex, &mipLevel);