GMs: fail gracefully for null surface

gm/image.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include <functional>
 #include "gm.h"
 #include "SkAutoPixmapStorage.h"
@@ skipping 240 matching lines @@
 
 static sk_sp<SkImage> make_codec(const SkImageInfo& info, GrContext*, void (*draw)(SkCanvas*)) {
     sk_sp<SkImage> image(make_raster(info, nullptr, draw));
     sk_sp<SkData> data(image->encode());
     return SkImage::MakeFromEncoded(data);
 }
 
 static sk_sp<SkImage> make_gpu(const SkImageInfo& info, GrContext* ctx, void (*draw)(SkCanvas*)) {
     if (!ctx) { return nullptr; }
     auto surface(SkSurface::MakeRenderTarget(ctx, SkBudgeted::kNo, info));
+    if (!surface) { return nullptr; }
     draw(surface->getCanvas());
     return surface->makeImageSnapshot();
 }
 
 typedef sk_sp<SkImage> (*ImageMakerProc)(const SkImageInfo&, GrContext*, void (*)(SkCanvas*));
 
 class ScalePixelsGM : public skiagm::GM {
 public:
     ScalePixelsGM() {}
 
@@ skipping 229 matching lines @@
         }
         if (context) {
             sk_sp<SkImage> texImage(image->makeTextureImage(context));
             if (texImage) {
                 canvas->drawImage(texImage, 0, 0);
             }
         }
         canvas->translate(image->width() + kPad, 0);
     }
 }