Revert of Delete base/prefs and update callers to use components.

extensions/shell/browser/shell_prefs_unittest.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/shell/browser/shell_prefs.h"
 
 #include "base/macros.h"
 #include "base/path_service.h"
+#include "base/prefs/pref_service.h"
 #include "build/build_config.h"
-#include "components/prefs/pref_service.h"
 #include "components/user_prefs/user_prefs.h"
 #include "content/public/test/test_browser_context.h"
 #include "content/public/test/test_browser_thread_bundle.h"
 #include "extensions/common/extension_paths.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace extensions {
 namespace {
 
 // A BrowserContext that uses a test data directory as its data path.
@@ skipping 50 matching lines @@
   // User prefs from the file have been read correctly.
   EXPECT_EQ("1.2.3.4", service->GetString("extensions.last_chrome_version"));
   EXPECT_EQ(123, service->GetInteger("extensions.toolbarsize"));
 
   // The user prefs system has been initialized.
   EXPECT_EQ(service.get(), user_prefs::UserPrefs::Get(&browser_context_));
 }
 
 }  // namespace
 }  // namespace extensions