Instrument direct surfaces of FeaturePolicy.

Bug: 973801
Change-Id: I047c76f8fd782dc7dce5486597b73fa5941c4bd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2363400Reviewed-by: Ian Clelland <iclelland@chromium.org>
Commit-Queue: Caleb Raitto <caraitto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#800151}

third_party/blink/renderer/core/feature_policy/feature_policy.idl

@@ -8,7 +8,7 @@
   ImplementedAs=DOMFeaturePolicy
 ] interface FeaturePolicy {
   [MeasureAs=FeaturePolicyJSAPI, CallWith=ScriptState] boolean allowsFeature(DOMString feature, optional DOMString origin);
-  [MeasureAs=FeaturePolicyJSAPI, CallWith=ScriptState] sequence<DOMString> features();
+  [HighEntropy=Direct, MeasureAs=FeaturePolicyJSAPI, CallWith=ScriptState] sequence<DOMString> features();
   [MeasureAs=FeaturePolicyJSAPI, CallWith=ScriptState] sequence<DOMString> allowedFeatures();
   [MeasureAs=FeaturePolicyJSAPI, CallWith=ScriptState] sequence<DOMString> getAllowlistForFeature(DOMString feature);
 };