[DurableStorage] Add UseCounter and fixed IDL

third_party/WebKit/Source/modules/quota/StorageManager.idl

 // Copyright 2015 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.
 
 // https://storage.spec.whatwg.org/#storagemanager
 
 [
     Exposed=(Window,Worker),
-    RuntimeEnabled=DurableStorage,
+    OriginTrialEnabled=DurableStorage,
 ] interface StorageManager {
-    [CallWith=ScriptState] Promise<boolean> persisted();
-    [Exposed=Window, CallWith=ScriptState] Promise<boolean> persist();
+    [CallWith=ScriptState, MeasureAs=DurableStoragePersisted] Promise<boolean> persisted();
+    [Exposed=Window, CallWith=ScriptState, MeasureAs=DurableStoragePersist] Promise<boolean> persist();
 
-    [RuntimeEnabled=StorageEstimate, CallWith=ScriptState] Promise<StorageEstimate> estimate();
+    [RuntimeEnabled=StorageEstimate, CallWith=ScriptState, MeasureAs=DurableStorageEstimate] Promise<StorageEstimate> estimate();

[chasej, 2016/05/17 03:00:42]

Given that estimate() isn't being exposed as part of the origin trial, this
method doesn't need [MeasureAs] for that reason. I think it's certainly
reasonable to add it now. I'm just mentioning in case there was confusion.

 };