Measure usage of RTCSessionDescription's type and sdp attributes

third_party/WebKit/Source/modules/peerconnection/RTCSessionDescription.idl

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 10 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-// http://www.w3.org/TR/webrtc/#idl-def-RTCSessionDescription
+// https://w3c.github.io/webrtc-pc/#rtcsessiondescription-class
 
 enum RTCSdpType {
     "offer",
     "pranswer",
     "answer"
+    // TODO(foolip): "rollback" is in the spec and Gecko's IDL.
 };
 
 [
-    Constructor(optional RTCSessionDescriptionInit descriptionInitDict)
+    Constructor(optional RTCSessionDescriptionInit descriptionInitDict),
+    ConstructorCallWith=ExecutionContext,
 ] interface RTCSessionDescription {
-    attribute RTCSdpType? type;
-    attribute DOMString? sdp;
+    // TODO(foolip): |type| and |sdp| should be readonly and not nullable.
+    // https://crbug.com/662898
+    [Measure] attribute RTCSdpType? type;
+    [Measure] attribute DOMString? sdp;
     serializer = {attribute};
 };