Check for null context

skia/ext/bitmap_platform_device_mac.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "skia/ext/bitmap_platform_device_mac.h"
 
 #import <ApplicationServices/ApplicationServices.h>
 #include <time.h>
 
 #include "base/mac/mac_util.h"
@@ skipping 125 matching lines @@
 
   // If we were given data, then don't clobber it!
 #ifndef NDEBUG
   if (!context && is_opaque) {
     // To aid in finding bugs, we set the background color to something
     // obviously wrong so it will be noticable when it is not cleared
     bitmap.eraseARGB(255, 0, 255, 128);  // bright bluish green
   }
 #endif
 
-  if (!context)
+  if (!context) {
     context = CGContextForData(data, width, height);
-  else
+    if (!context)
+      return NULL;
+  } else
     CGContextRetain(context);
 
   BitmapPlatformDevice* rv = new BitmapPlatformDevice(
       new BitmapPlatformDeviceData(context), bitmap);
 
   // The device object took ownership of the graphics context with its own
   // CGContextRetain call.
   CGContextRelease(context);
 
   return rv;
@@ skipping 77 matching lines @@
 }
 
 SkDevice* BitmapPlatformDevice::onCreateCompatibleDevice(
     SkBitmap::Config config, int width, int height, bool isOpaque,
     Usage /*usage*/) {
   SkASSERT(config == SkBitmap::kARGB_8888_Config);
   return BitmapPlatformDevice::Create(NULL, width, height, isOpaque);
 }
 
 }  // namespace skia