Revert "Revert of https://codereview.chromium.org/108773003/"

src/gpu/GrSurface.cpp

Index: src/gpu/GrSurface.cpp
diff --git a/src/gpu/GrSurface.cpp b/src/gpu/GrSurface.cpp
index fed95f232fe4b18d34ef4f6d7844346aacc44eba..1fcc4ff18be23eeb51dc843489a32c00dfbbf685 100644
--- a/src/gpu/GrSurface.cpp
+++ b/src/gpu/GrSurface.cpp
@@ -8,9 +8,19 @@
 #include "GrSurface.h"
 
 #include "SkBitmap.h"
+#include "SkGr.h"
 #include "SkImageEncoder.h"
 #include <stdio.h>
 
+void GrSurface::asImageInfo(SkImageInfo* info) const {
+    if (!GrPixelConfig2ColorType(this->config(), &info->fColorType)) {
+        sk_throw();
+    }
+    info->fWidth = this->width();
+    info->fHeight = this->height();
+    info->fAlphaType = kPremul_SkAlphaType;
+}
+
 bool GrSurface::savePixels(const char* filename) {
     SkBitmap bm;
     bm.setConfig(SkBitmap::kARGB_8888_Config, this->width(), this->height());