App launcher: Avoid a browser crash if the custom page renderer crashes.

chrome/browser/ui/app_list/app_list_view_delegate.cc

 // 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/app_list/app_list_view_delegate.h"
 
 #include <vector>
 
 #include "apps/custom_launcher_page_contents.h"
 #include "base/callback.h"
@@ skipping 696 matching lines @@
   for (ScopedVector<apps::CustomLauncherPageContents>::const_iterator it =
            custom_page_contents_.begin();
        it != custom_page_contents_.end();
        ++it) {
     content::WebContents* web_contents = (*it)->web_contents();
 
     // The web contents should belong to the current profile.
     DCHECK_EQ(profile_, web_contents->GetBrowserContext());
 
     // Make the webview transparent.
-    web_contents->GetRenderViewHost()->GetView()->SetBackgroundColor(
-        SK_ColorTRANSPARENT);
+    content::RenderWidgetHostView* render_view_host_view =
+        web_contents->GetRenderViewHost()->GetView();
+    // The RenderWidgetHostView may be null if the renderer has crashed.
+    if (render_view_host_view)
+      render_view_host_view->SetBackgroundColor(SK_ColorTRANSPARENT);
 
     views::WebView* web_view =
         new views::WebView(web_contents->GetBrowserContext());
     web_view->SetPreferredSize(size);
     web_view->SetResizeBackgroundColor(SK_ColorTRANSPARENT);
     web_view->SetWebContents(web_contents);
     web_views.push_back(web_view);
   }
 
   return web_views;
@@ skipping 83 matching lines @@
 
       // SigninManagerFactory is not a leaky singleton (unlike this class), and
       // its destructor will check that it has no remaining observers.
       scoped_observer_.RemoveAll();
       SigninManagerFactory::GetInstance()->RemoveObserver(this);
       break;
     default:
       NOTREACHED();
   }
 }