[Extensions Page MD] Stub out a materialized extensions page

chrome/browser/browser_about_handler.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/browser_about_handler.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 37 matching lines @@
   if (host == chrome::kChromeUIAboutHost)
     host = chrome::kChromeUIChromeURLsHost;
   // Replace cache with view-http-cache.
   if (host == chrome::kChromeUICacheHost) {
     host = content::kChromeUINetworkViewCacheHost;
   // Replace sync with sync-internals (for legacy reasons).
   } else if (host == chrome::kChromeUISyncHost) {
     host = chrome::kChromeUISyncInternalsHost;
   // Redirect chrome://extensions.
   } else if (host == chrome::kChromeUIExtensionsHost) {
-    host = chrome::kChromeUIUberHost;
-    path = chrome::kChromeUIExtensionsHost + url->path();
+    // If the material design extensions page is enabled, it gets its own host.
+    // Otherwise, it's handled by the uber settings page.
+    if (::switches::MdExtensionsEnabled()) {
+      host = chrome::kChromeUIExtensionsHost;
+      path = url->path();
+    } else {
+      host = chrome::kChromeUIUberHost;
+      path = chrome::kChromeUIExtensionsHost + url->path();
+    }
   // Redirect chrome://settings/extensions (legacy URL).
   } else if (host == chrome::kChromeUISettingsHost &&
       url->path() == std::string("/") + chrome::kExtensionsSubPage) {
     host = chrome::kChromeUIUberHost;
     path = chrome::kChromeUIExtensionsHost;
   // Redirect chrome://history.
   } else if (host == chrome::kChromeUIHistoryHost) {
 #if defined(OS_ANDROID)
     // On Android, redirect directly to chrome://history-frame since
     // uber page is unsupported.
@@ skipping 42 matching lines @@
         FROM_HERE, base::Bind(&chrome::AttemptRestart));
     return true;
   } else if (base::LowerCaseEqualsASCII(spec, chrome::kChromeUIQuitURL)) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::Bind(&chrome::AttemptExit));
     return true;
   }
 
   return false;
 }