Fail gracefully if MakeRenderTarget fails

gm/image_shader.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "gm.h"
 #include "SkCanvas.h"
 #include "SkData.h"
@@ skipping 20 matching lines @@
     surface->getCanvas()->clear(0);
     surface->getCanvas()->drawPicture(pic);
     return surface->makeImageSnapshot();
 }
 
 static sk_sp<SkImage> make_texture(GrContext* ctx, SkPicture* pic, const SkImageInfo& info) {
     if (!ctx) {
         return nullptr;
     }
     auto surface(SkSurface::MakeRenderTarget(ctx, SkBudgeted::kNo, info));
+    if (!surface) {
+        return nullptr;
+    }
     surface->getCanvas()->clear(0);
     surface->getCanvas()->drawPicture(pic);
     return surface->makeImageSnapshot();
 }
 
 static sk_sp<SkImage> make_pict_gen(GrContext*, SkPicture* pic, const SkImageInfo& info) {
     return SkImage::MakeFromPicture(sk_ref_sp(pic), info.dimensions(), nullptr, nullptr);
 }
 
 static sk_sp<SkImage> make_encode_gen(GrContext* ctx, SkPicture* pic, const SkImageInfo& info) {
@@ skipping 66 matching lines @@
                 this->testImage(canvas, image.get());
             }
             canvas->translate(120, 0);
         }
     }
 
 private:
     typedef skiagm::GM INHERITED;
 };
 DEF_GM( return new ImageShaderGM; )