exhibit 1: explicit null checks

chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.mm

 // Copyright (c) 2012 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 "chrome/browser/ui/cocoa/tab_contents/favicon_util_mac.h"
 
 #include "chrome/browser/favicon/favicon_tab_helper.h"
 #include "chrome/browser/ui/tab_contents/tab_contents.h"
 #include "grit/ui_resources.h"
 #include "ui/base/resource/resource_bundle.h"
 
 namespace mac {
 
 NSImage* FaviconForTabContents(TabContents* contents) {
   if (contents && contents->favicon_tab_helper()->FaviconIsValid()) {
-    NSImage* image = contents->favicon_tab_helper()->GetFavicon().AsNSImage();
-    // The |image| could be nil if the bitmap is null. In that case, fallback
-    // to the default image.
-    if (image) {
-      return image;
-    }
+    const gfx::Image& icon = contents->favicon_tab_helper()->GetFavicon();
+    if (!icon.IsEmpty())
+      return icon.ToNSImage();;
   }
 
+  // Fall back to the default image.
   ResourceBundle& rb = ResourceBundle::GetSharedInstance();
   return rb.GetNativeImageNamed(IDR_DEFAULT_FAVICON);
 }
 
 }  // namespace mac