Don't try to create extensionoptions for extensions that don't exist.

extensions/browser/guest_view/extension_options/extension_options_guest.cc

 // Copyright 2014 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 "extensions/browser/guest_view/extension_options/extension_options_guest.h"
 
 #include "base/values.h"
 #include "components/crx_file/id_util.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/site_instance.h"
@@ skipping 73 matching lines @@
   if (!extension_url.is_valid()) {
     callback.Run(NULL);
     return;
   }
 
   // Get the options page URL for later use.
   extensions::ExtensionRegistry* registry =
       extensions::ExtensionRegistry::Get(browser_context());
   const extensions::Extension* extension =
       registry->enabled_extensions().GetByID(extension_id);
+  if (!extension) {
+    // The ID was valid but the extension didn't exist. Typically this will
+    // happen when an extension is disabled.
+    callback.Run(NULL);
+    return;
+  }
+
   options_page_ = extensions::OptionsPageInfo::GetOptionsPage(extension);
   if (!options_page_.is_valid()) {
     callback.Run(NULL);
     return;
   }
 
   // Create a WebContents using the extension URL. The options page's
   // WebContents should live in the same process as its parent extension's
   // WebContents, so we can use |extension_url| for creating the SiteInstance.
   content::SiteInstance* options_site_instance =
@@ skipping 155 matching lines @@
   attach_params()->GetInteger(extensionoptions::kAttributeMinWidth, &min_width);
 
   // Call SetAutoSize to apply all the appropriate validation and clipping of
   // values.
   SetAutoSize(auto_size_enabled,
               gfx::Size(min_width, min_height),
               gfx::Size(max_width, max_height));
 }
 
 }  // namespace extensions