Count usage of MediaStream active and inactive events

third_party/WebKit/Source/modules/mediastream/MediaStream.idl

Index: third_party/WebKit/Source/modules/mediastream/MediaStream.idl
diff --git a/third_party/WebKit/Source/modules/mediastream/MediaStream.idl b/third_party/WebKit/Source/modules/mediastream/MediaStream.idl
index f90d75f2e5823afc487dec981c92b0a6e4445dae..f59564f74f394242da3c7f21a1610660433f74b1 100644
--- a/third_party/WebKit/Source/modules/mediastream/MediaStream.idl
+++ b/third_party/WebKit/Source/modules/mediastream/MediaStream.idl
@@ -45,8 +45,8 @@
 
     readonly attribute boolean active;
 
-    attribute EventHandler onactive;
-    attribute EventHandler oninactive;
+    [MeasureAs=MediaStreamOnActive] attribute EventHandler onactive;

[foolip, 2016/06/22 12:17:05]

I think you shouldn't actually need to measure this. If one assigns an event
listener, doesn't it reach addEventListenerInternal anyway? If it doesn't, can
you count where the code paths meet?

The potential problem here is that the counter will be triggered by merely
reading the attributes, which could happen by enumerating attributes. This
completely poisons use counters for attributes on Window, Document and Event,
and it's hard to guess if it might play in here too.

+    [MeasureAs=MediaStreamOnInactive] attribute EventHandler oninactive;
     //  DEPRECATED
     [DeprecateAs=MediaStreamOnEnded] attribute EventHandler onended;