Move system.* family of APIs to extensions/

chrome/common/extensions/api/system_memory.idl

-// 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.
-
-// The <code>chrome.system.memory</code> API.
-namespace system.memory {
-
-  dictionary MemoryInfo {
-    // The total amount of physical memory capacity, in bytes.
-    double capacity;
-    // The amount of available capacity, in bytes.
-    double availableCapacity;
-  };
-
-  callback MemoryInfoCallback = void (MemoryInfo info);
-
-  interface Functions {
-    // Get physical memory information.
-    static void getInfo(MemoryInfoCallback callback);
-  };
-};