Fix MetricsServiceClients to use SyncDisableObservers state.

ios/chrome/browser/metrics/ios_chrome_metrics_service_client.mm

Index: ios/chrome/browser/metrics/ios_chrome_metrics_service_client.mm
diff --git a/ios/chrome/browser/metrics/ios_chrome_metrics_service_client.mm b/ios/chrome/browser/metrics/ios_chrome_metrics_service_client.mm
index 71d8b8098c2a5f0a6a235870314bf09d52b3c548..090f53fa0990a64872f645287920af2e73b7fb83 100644
--- a/ios/chrome/browser/metrics/ios_chrome_metrics_service_client.mm
+++ b/ios/chrome/browser/metrics/ios_chrome_metrics_service_client.mm
@@ -374,3 +374,7 @@ void IOSChromeMetricsServiceClient::OnSyncPrefsChanged(bool must_purge) {
   // Signal service manager to enable/disable UKM based on new state.
   UpdateRunningServices();
 }
+
+bool IOSChromeMetricsServiceClient::IsHistorySyncEnabledOnAllProfiles() {
+  return SyncDisableObserver::IsHistorySyncEnabledOnAllProfiles();
+}