[Extensions] Move [Chrome]ExtensionTestNotificationObserver into extensions::

chrome/browser/ui/webui/extensions/extension_settings_browsertest.cc

 // Copyright 2013 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/webui/extensions/extension_settings_browsertest.h"
 
 #include <stddef.h>
 #include <utility>
 
 #include "base/files/file_path.h"
@@ skipping 40 matching lines @@
 Profile* ExtensionSettingsUIBrowserTest::GetProfile() {
   if (!profile_) {
     profile_ = browser() ? browser()->profile() :
                            ProfileManager::GetActiveUserProfile();
   }
   return profile_;
 }
 
 void ExtensionSettingsUIBrowserTest::SetUpOnMainThread() {
   WebUIBrowserTest::SetUpOnMainThread();
-  observer_.reset(new ChromeExtensionTestNotificationObserver(browser()));
+  observer_.reset(
+      new extensions::ChromeExtensionTestNotificationObserver(browser()));
 }
 
 void ExtensionSettingsUIBrowserTest::InstallGoodExtension() {
   EXPECT_TRUE(InstallExtension(test_data_dir_.AppendASCII("good.crx")));
 }
 
 void ExtensionSettingsUIBrowserTest::InstallErrorsExtension() {
   EXPECT_TRUE(InstallUnpackedExtension(
       test_data_dir_.AppendASCII("error_console")
                     .AppendASCII("runtime_and_manifest_errors")));
@@ skipping 123 matching lines @@
          iter != errors->end(); ++iter)
       VLOG(1) << *iter;
 
     return nullptr;
   }
 
   if (!observer_->WaitForExtensionViewsToLoad())
     return nullptr;
   return service->GetExtensionById(last_loaded_extension_id(), false);
 }