Add use counters for user prompt methods

This change adds use counters for the following methods on window:
 - alert()
 - confirm()
 - prompt()
 - print()

Review URL: https://codereview.chromium.org/1325193007

git-svn-id: svn://svn.chromium.org/blink/trunk@202018 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/frame/UseCounter.h

@@ -842,6 +842,10 @@ public:
         NetInfoDownlinkMax = 947,
         NetInfoOnChange = 948,
         NetInfoOnTypeChange = 949,
+        V8Window_Alert_Method = 950,
+        V8Window_Confirm_Method = 951,
+        V8Window_Prompt_Method = 952,
+        V8Window_Print_Method = 953,
 
         // Add new features immediately above this line. Don't change assigned
         // numbers of any item, and don't reuse removed slots.

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

@@ -72,11 +72,11 @@
     [RuntimeEnabled=ApplicationCache, LogActivity=GetterOnly] readonly attribute ApplicationCache applicationCache;
 
     // user prompts
-    void alert();
-    void alert(DOMString message);
-    boolean confirm(optional DOMString message = "");
-    DOMString? prompt(optional DOMString message = "", optional DOMString defaultValue = "");
-    void print();
+    [Measure] void alert();
+    [Measure] void alert(DOMString message);
+    [Measure] boolean confirm(optional DOMString message = "");
+    [Measure] DOMString? prompt(optional DOMString message = "", optional DOMString defaultValue = "");
+    [Measure] void print();
 
     [MeasureAs=UnprefixedRequestAnimationFrame] long requestAnimationFrame(FrameRequestCallback callback);
     void cancelAnimationFrame(long handle);