Count instances of `javascript:` URL execution.

We're currently measuring whether or not a document is replaced by
the execution of a JavaScript URL (e.g. if the JavaScript resulted
in a string during navigation, in which case we navigate to a doc
whose body is that string). We should figure out how many pageviews
rely on `javascript:` execution generally, as that's going to be a
larger number.

R=andypaicu@chromium.org

Change-Id: I474ed7a5072f99e90ddab56351fbc8e5fe327909
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1698529
Commit-Queue: Andy Paicu <andypaicu@chromium.org>
Reviewed-by: Andy Paicu <andypaicu@chromium.org>
Auto-Submit: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676854}

third_party/blink/public/mojom/web_feature/web_feature.mojom

@@ -2341,6 +2341,7 @@ enum WebFeature {
   kDiscardInputEventToMovingIframe = 2952,
   kSignedExchangeSubresourcePrefetch = 2953,
   kBasicCardType = 2954,
+  kExecutedJavaScriptURL = 2955,
 
   // Add new features immediately above this line. Don't change assigned
   // numbers of any item, and don't reuse removed slots.

third_party/blink/renderer/bindings/core/v8/script_controller.cc

@@ -273,6 +273,8 @@ void ScriptController::ExecuteJavaScriptURL(
       ScriptSourceCode(script_source, ScriptSourceLocationType::kJavascriptUrl),
       base_url, SanitizeScriptErrors::kDoNotSanitize, ScriptFetchOptions(),
       kDoNotExecuteScriptWhenScriptsDisabled);
+  UseCounter::Count(*GetFrame()->GetDocument(),
+                    WebFeature::kExecutedJavaScriptURL);
 
   // If executing script caused this frame to be removed from the page, we
   // don't want to try to replace its document!

tools/metrics/histograms/enums.xml

@@ -23857,6 +23857,7 @@ Called by update_net_error_codes.py.-->
   <int value="2952" label="DiscardInputEventToMovingIframe"/>
   <int value="2953" label="SignedExchangeSubresourcePrefetch"/>
   <int value="2954" label="BasicCardType"/>
+  <int value="2955" label="ExecutedJavaScriptURL"/>
 </enum>
 
 <enum name="FeaturePolicyAllowlistType">