Removing extensions::FeatureSwitch which is no longer used

chrome/browser/extensions/extension_startup_browsertest.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 <vector>
 
 #include "base/command_line.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/path_service.h"
@@ skipping 18 matching lines @@
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/test/browser_test_utils.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/common/extension.h"
 #include "extensions/common/extension_set.h"
 #include "extensions/common/feature_switch.h"
 #include "net/base/filename_util.h"
 
-using extensions::FeatureSwitch;
 
 // This file contains high-level startup tests for the extensions system. We've
 // had many silly bugs where command line flags did not get propagated correctly
 // into the services, so we didn't start correctly.
 
 class ExtensionStartupTestBase : public InProcessBrowserTest {
  public:
   ExtensionStartupTestBase() : unauthenticated_load_allowed_(true) {
     num_expected_extensions_ = 3;
   }
@@ skipping 243 matching lines @@
         .AppendASCII("extensions")
         .AppendASCII("app2");
     load_extensions_.push_back(fourth_extension_path.value());
   }
 };
 
 IN_PROC_BROWSER_TEST_F(ExtensionsLoadMultipleTest, Test) {
   WaitForServicesToStart(4, true);
   TestInjection(true, true);
 }