Cache the current WebPreferences on RenderViewHostImpl.

chrome/browser/chrome_content_browser_client.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/chrome_content_browser_client.h"
 
 #include <set>
 #include <utility>
 #include <vector>
 
@@ skipping 2465 matching lines @@
   // Make sure we will set the default_encoding with canonical encoding name.
   web_prefs->default_encoding =
       CharacterEncoding::GetCanonicalEncodingNameByAliasName(
           web_prefs->default_encoding);
   if (web_prefs->default_encoding.empty()) {
     prefs->ClearPref(prefs::kDefaultCharset);
     web_prefs->default_encoding = prefs->GetString(prefs::kDefaultCharset);
   }
   DCHECK(!web_prefs->default_encoding.empty());
 
+  // Note: it's not posible for kExtensionsScheme to change during the lifetime
+  // of the process.
   WebContents* web_contents = WebContents::FromRenderViewHost(rvh);
   extensions::ViewType view_type = extensions::GetViewType(web_contents);
   ExtensionService* service =
       extensions::ExtensionSystem::Get(profile)->extension_service();
   if (service) {
     const GURL& site_url = rvh->GetSiteInstance()->GetSiteURL();
     const Extension* extension =
         service->extensions()->GetByID(site_url.host());
     // Ensure that we are only granting extension preferences to URLs with
     // the correct scheme. Without this check, chrome-guest:// schemes used by
@@ skipping 411 matching lines @@
       switches::kDisableWebRtcEncryption,
     };
     to_command_line->CopySwitchesFrom(from_command_line,
                                       kWebRtcDevSwitchNames,
                                       arraysize(kWebRtcDevSwitchNames));
   }
 }
 #endif  // defined(ENABLE_WEBRTC)
 
 }  // namespace chrome