GMs: fail gracefully for null surface

gm/image_pict.cpp

Index: gm/image_pict.cpp
diff --git a/gm/image_pict.cpp b/gm/image_pict.cpp
index fd7ac2adb12089efffa2b6619a8c4b5ae6f8d6c4..9d1dc513a8cbd74eba522595d90cc5937f12a2a8 100644
--- a/gm/image_pict.cpp
+++ b/gm/image_pict.cpp
@@ -212,11 +212,13 @@ public:
         , fCtx(SkRef(ctx))
     {
         auto surface(SkSurface::MakeRenderTarget(ctx, SkBudgeted::kNo, info));
-        surface->getCanvas()->clear(0);
-        surface->getCanvas()->translate(-100, -100);
-        surface->getCanvas()->drawPicture(pic);
-        sk_sp<SkImage> image(surface->makeImageSnapshot());
-        fTexture.reset(SkRef(as_IB(image)->peekTexture()));
+        if (surface) {
+            surface->getCanvas()->clear(0);
+            surface->getCanvas()->translate(-100, -100);
+            surface->getCanvas()->drawPicture(pic);
+            sk_sp<SkImage> image(surface->makeImageSnapshot());
+            fTexture.reset(SkRef(as_IB(image)->peekTexture()));
+        }
     }
 protected:
     GrTexture* onGenerateTexture(GrContext* ctx, const SkIRect* subset) override {
@@ -224,6 +226,10 @@ protected:
             SkASSERT(ctx == fCtx.get());
         }
 
+        if (!fTexture) {
+            return nullptr;
+        }
+
         if (!subset) {
             return SkRef(fTexture.get());
         }