"Fix" another crash on valgrind bot

tests/DeferredCanvasTest.cpp

 
 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "Test.h"
 #include "SkBitmap.h"
 #include "SkBitmapDevice.h"
@@ skipping 685 matching lines @@
         10,  // width
         10,  // height
         kPMColor_SkColorType,
         kPremul_SkAlphaType
     };
     SkSurface* surface;
     bool useGpu = NULL != factory;
 #if SK_SUPPORT_GPU
     if (useGpu) {
         GrContext* context = factory->get(GrContextFactory::kNative_GLContextType);
+        if (NULL == context) {
+            return;
+        }
+
         surface = SkSurface::NewRenderTarget(context, imageSpec);
     } else {
         surface = SkSurface::NewRaster(imageSpec);
     }
 #else
     SkASSERT(!useGpu);
     surface = SkSurface::NewRaster(imageSpec);
 #endif
     SkASSERT(NULL != surface);
     SkAutoTUnref<SkSurface> aur(surface);
@@ skipping 123 matching lines @@
     TestDeferredCanvasSurface(reporter, NULL);
     TestDeferredCanvasSetSurface(reporter, NULL);
     if (NULL != factory) {
         TestDeferredCanvasSurface(reporter, factory);
         TestDeferredCanvasSetSurface(reporter, factory);
     }
 }
 
 #include "TestClassDef.h"
 DEFINE_GPUTESTCLASS("DeferredCanvas", TestDeferredCanvasClass, TestDeferredCanvas)