Revert of Add ExtensionsApiClient interface, use it in the storage API SettingsFrontend

extensions/browser/api/storage/settings_namespace.h

Index: extensions/browser/api/storage/settings_namespace.h
diff --git a/extensions/browser/api/storage/settings_namespace.h b/extensions/browser/api/storage/settings_namespace.h
deleted file mode 100644
index 7a5a8126abd007ecf6f3e3a3d1e0914a32bab53e..0000000000000000000000000000000000000000
--- a/extensions/browser/api/storage/settings_namespace.h
+++ /dev/null
@@ -1,34 +0,0 @@
-// 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.
-
-#ifndef EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_NAMESPACE_H_
-#define EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_NAMESPACE_H_
-
-#include <string>
-
-namespace extensions {
-
-namespace settings_namespace {
-
-// The namespaces of the storage areas.
-enum Namespace {
-  LOCAL,    // "local"    i.e. chrome.storage.local
-  SYNC,     // "sync"     i.e. chrome.storage.sync
-  MANAGED,  // "managed"  i.e. chrome.storage.managed
-  INVALID
-};
-
-// Converts a namespace to its string representation.
-// Namespace must not be INVALID.
-std::string ToString(Namespace settings_namespace);
-
-// Converts a string representation of a namespace to its namespace, or INVALID
-// if the string doesn't map to one.
-Namespace FromString(const std::string& ns_string);
-
-}  // namespace settings_namespace
-
-}  // namespace extensions
-
-#endif  // EXTENSIONS_BROWSER_API_STORAGE_SETTINGS_NAMESPACE_H_