Add use counters for lots of DOM APIs.

third_party/WebKit/Source/core/frame/WindowEventHandlers.idl

Index: third_party/WebKit/Source/core/frame/WindowEventHandlers.idl
diff --git a/third_party/WebKit/Source/core/frame/WindowEventHandlers.idl b/third_party/WebKit/Source/core/frame/WindowEventHandlers.idl
index 63748031de7e9ea9a26f6c66a35d8364fae9432b..a30abf712fb818a9068565471d59a1f66980c17d 100644
--- a/third_party/WebKit/Source/core/frame/WindowEventHandlers.idl
+++ b/third_party/WebKit/Source/core/frame/WindowEventHandlers.idl
@@ -37,17 +37,17 @@
     //attribute EventHandler onafterprint;
     //attribute EventHandler onbeforeprint;
     // FIXME: onbeforeunload should be an OnBeforeUnloadEventHandler.
-    attribute EventHandler onbeforeunload;
-    attribute EventHandler onhashchange;
-    attribute EventHandler onlanguagechange;
-    attribute EventHandler onmessage;
-    attribute EventHandler onoffline;
-    attribute EventHandler ononline;
-    attribute EventHandler onpagehide;
-    attribute EventHandler onpageshow;
-    attribute EventHandler onpopstate;
-    attribute EventHandler onrejectionhandled;
-    attribute EventHandler onstorage;
-    attribute EventHandler onunhandledrejection;
-    attribute EventHandler onunload;
+    [Measure] attribute EventHandler onbeforeunload;
+    [Measure] attribute EventHandler onhashchange;
+    [Measure] attribute EventHandler onlanguagechange;
+    [Measure] attribute EventHandler onmessage;
+    [Measure] attribute EventHandler onoffline;
+    [Measure] attribute EventHandler ononline;
+    [Measure] attribute EventHandler onpagehide;
+    [Measure] attribute EventHandler onpageshow;
+    [Measure] attribute EventHandler onpopstate;
+    [Measure] attribute EventHandler onrejectionhandled;
+    [Measure] attribute EventHandler onstorage;
+    [Measure] attribute EventHandler onunhandledrejection;
+    [Measure] attribute EventHandler onunload;
 };