Convert first contentful paint logging to the new UKM client API

components/ukm/ukm_service.cc

Index: components/ukm/ukm_service.cc
diff --git a/components/ukm/ukm_service.cc b/components/ukm/ukm_service.cc
index 06c3dbb5f59a60870f12b910eca9dd3289dc12db..3bf440f3a1c80d743370d7cafbbe30a55b298d8e 100644
--- a/components/ukm/ukm_service.cc
+++ b/components/ukm/ukm_service.cc
@@ -229,6 +229,12 @@ void UkmService::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterListPref(prefs::kUkmPersistedLogs);
 }
 
+// static
+int32_t UkmService::NewSourceId() {
+  static int32_t g_source_id_provider = 0;
+  return g_source_id_provider++;
+}
+
 void UkmService::StartInitTask() {
   DCHECK(thread_checker_.CalledOnValidThread());
   DVLOG(1) << "UkmService::StartInitTask";
@@ -387,7 +393,7 @@ void UkmService::UpdateSourceURL(int32_t source_id, const GURL& url) {
     if (source_id != source->id())
       continue;
 
-    source->set_committed_url(url);
+    source->set_url(url);
     return;
   }
 
@@ -397,7 +403,7 @@ void UkmService::UpdateSourceURL(int32_t source_id, const GURL& url) {
   }
   std::unique_ptr<UkmSource> source = base::MakeUnique<UkmSource>();
   source->set_id(source_id);
-  source->set_committed_url(url);
+  source->set_url(url);
   sources_.push_back(std::move(source));
 }