Implement Web Restrictions in WebView.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 1fc712068a1667c17ac96b19d86f566c563fcfaa..9ee1765333e7612a903399c4adb8a2aa790c312f 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -56827,6 +56827,33 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="SupervisedUserContentProvider.ChromeNotStartedRequestTime"
+    units="ms">
+  <owner>aberent@chromium.org</owner>
+  <summary>
+    Time to get the response to requesting whether a URL should be accessible to
+    the supervised user, when Chrome was not previously running.
+  </summary>
+</histogram>
+
+<histogram name="SupervisedUserContentProvider.ChromeStartedRequestTime"
+    units="ms">
+  <owner>aberent@chromium.org</owner>
+  <summary>
+    Time to get the response to requesting whether a URL should be accessible to
+    the supervised user, when Chrome was already running.
+  </summary>
+</histogram>
+
+<histogram name="SupervisedUserContentProvider.RequestTimedOut"
+    enum="BooleanTimedOut">
+  <owner>aberent@chromium.org</owner>
+  <summary>
+    True if a request to find out whether a URL should be accessible to a
+    supervised user timed out.
+  </summary>
+</histogram>
+
 <histogram name="Sync.AppAssociationTime" units="ms">
   <obsolete>
     Deprecated in M53.
@@ -73579,6 +73606,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="337" label="Enable Android Backup Service"/>
   <int value="338"
       label="Enable generated content suggestions on the New Tab page"/>
+  <int value="339" label="Set an external source of URL restrictions"/>
 </enum>
 
 <enum name="EnterprisePolicyInvalidations" type="int">