Instrument calls to Navigator.javaEnabled().

This cl causes the bindings generator to automatically collect UKM when
|Navigator.javaEnabled| is called. This will be used to analyze how much
entropy leaked by this API can be used for cross-site tracking.

Bug: 973801
Change-Id: I5d6c24996680d9776a34300ed765a614a9518fbb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2423585Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Chris Fredrickson <cfredric@google.com>
Cr-Commit-Position: refs/heads/master@{#809755}

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

@@ -2808,7 +2808,7 @@ enum WebFeature {
   kIdentifiabilityStudyReserved3478 = 3478,
   kIdentifiabilityStudyReserved3479 = 3479,
   kIdentifiabilityStudyReserved3480 = 3480,
-  kIdentifiabilityStudyReserved3481 = 3481,
+  kV8Navigator_JavaEnabled_Method = 3481,
   kIdentifiabilityStudyReserved3482 = 3482,
   kIdentifiabilityStudyReserved3483 = 3483,
   kIdentifiabilityStudyReserved3484 = 3484,

third_party/blink/renderer/modules/plugins/navigator_plugins.idl

@@ -8,5 +8,5 @@
 ] partial interface Navigator {
     [HighEntropy, MeasureAs=NavigatorPlugins] readonly attribute PluginArray plugins;
     [HighEntropy, MeasureAs=NavigatorMimeTypes] readonly attribute MimeTypeArray mimeTypes;
-    boolean javaEnabled();
+    [HighEntropy=Direct, Measure] boolean javaEnabled();
 };

tools/metrics/histograms/enums.xml

@@ -29245,7 +29245,7 @@ Called by update_use_counter_feature_enum.py.-->
   <int value="3478" label="IdentifiabilityStudyReserved3478"/>
   <int value="3479" label="IdentifiabilityStudyReserved3479"/>
   <int value="3480" label="IdentifiabilityStudyReserved3480"/>
-  <int value="3481" label="IdentifiabilityStudyReserved3481"/>
+  <int value="3481" label="V8Navigator_JavaEnabled_Method"/>
   <int value="3482" label="IdentifiabilityStudyReserved3482"/>
   <int value="3483" label="IdentifiabilityStudyReserved3483"/>
   <int value="3484" label="IdentifiabilityStudyReserved3484"/>