Measure usage of createObjectURL and srcObject

third_party/WebKit/Source/modules/srcobject/HTMLMediaElementSrcObject.idl

 // Copyright 2016 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://html.spec.whatwg.org/multipage/embedded-content.html#dom-media-srcobject
 
 // TODO(guidou): Add support for MediaSource and Blob, as defined in the spec.
 typedef MediaStream MediaProvider;
 
 partial interface HTMLMediaElement {
     // TODO(haraken): Per the spec, the srcObject should be defined in
     // HTMLMediaElement.idl. However, we cannot define srcObject in
     // HTMLMediaElement.idl because of the dependency restriction from modules/
     // to core/. For now we avoid the problem by using a partial interface.
-    attribute MediaProvider? srcObject;
+    [Measure] attribute MediaProvider? srcObject;
 };