Add enterprise policy for network time service

components/network_time/network_time_tracker.cc

Index: components/network_time/network_time_tracker.cc
diff --git a/components/network_time/network_time_tracker.cc b/components/network_time/network_time_tracker.cc
index b5d8ccb853831daf89f93e1282e7386cd454ed17..56331529789d5286c5ca1a49158f3bf14160cef9 100644
--- a/components/network_time/network_time_tracker.cc
+++ b/components/network_time/network_time_tracker.cc
@@ -191,6 +191,7 @@ void RecordFetchValidHistogram(bool valid) {
 void NetworkTimeTracker::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterDictionaryPref(prefs::kNetworkTimeMapping,
                                    base::MakeUnique<base::DictionaryValue>());
+  registry->RegisterBooleanPref(prefs::kNetworkTimeQueriesEnabled, true);
 }
 
 NetworkTimeTracker::NetworkTimeTracker(
@@ -478,7 +479,11 @@ void NetworkTimeTracker::CheckTime() {
         policy {
           cookies_allowed: false
           setting: "This feature cannot be disabled by settings."
-          policy_exception_justification: "Not implemented."
+          chrome_policy {
+            NetworkTimeQueriesEnabled {
+                NetworkTimeQueriesEnabled: false
+            }
+          }
         })");
   // This cancels any outstanding fetch.
   time_fetcher_ = net::URLFetcher::Create(url, net::URLFetcher::GET, this,
@@ -621,6 +626,11 @@ bool NetworkTimeTracker::ShouldIssueTimeQuery() {
     return false;
   }
 
+  // Do not query the time service if queries are disabled by policy.
+  if (!pref_service_->GetBoolean(prefs::kNetworkTimeQueriesEnabled)) {
+    return false;
+  }
+
   // If GetNetworkTime() does not return NETWORK_TIME_AVAILABLE,
   // synchronization has been lost and a query is needed.
   base::Time network_time;