[SystemInfo API] Move Storage API out of experimental namespace and rename to the "system" namespace

chrome/common/extensions/api/_api_features.json

 // 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.
 
 // See c/c/e/features/* to understand this file, in particular feature.h,
 // simple_feature.h, and base_feature_provider.h.
 
 {
   "activityLogPrivate": {
     "dependencies": ["permission:activityLogPrivate"],
@@ skipping 446 matching lines @@
     "contexts": ["blessed_extension"]
   },
   "systemInfo.display": {
     "dependencies": ["permission:systemInfo.display"],
     "contexts": ["blessed_extension"]
   },
   "systemInfo.memory": {
     "dependencies": ["permission:systemInfo.memory"],
     "contexts": ["blessed_extension"]
   },
+  "systemInfo.storage": {
+    "dependencies": ["permission:systemInfo.storage"],
+    "contexts": ["blessed_extension"]
+  },
   "systemPrivate": {
     "dependencies": ["permission:systemPrivate"],
     "contexts": ["blessed_extension"]
   },
   "tabCapture": {
     "dependencies": ["permission:tabCapture"],
     "contexts": ["blessed_extension"]
   },
   "tabs": {
     "channel": "stable",
@@ skipping 72 matching lines @@
   },
   "webview": {
     "dependencies": ["permission:webview"],
     "contexts": ["blessed_extension"]
   },
   "windows": {
     "dependencies": ["permission:tabs"],
     "contexts": ["blessed_extension"]
   }
 }