Decouple iOS port from ChromeMetricsServiceClient

ios/chrome/browser/prefs/browser_prefs.mm

Index: ios/chrome/browser/prefs/browser_prefs.mm
diff --git a/ios/chrome/browser/prefs/browser_prefs.mm b/ios/chrome/browser/prefs/browser_prefs.mm
index 6776246798f17d436add31a605822751e57ed747..017eb4e345428880307be534679c053538ca7ce4 100644
--- a/ios/chrome/browser/prefs/browser_prefs.mm
+++ b/ios/chrome/browser/prefs/browser_prefs.mm
@@ -29,6 +29,7 @@
 #include "ios/chrome/browser/first_run/first_run.h"
 #import "ios/chrome/browser/geolocation/omnibox_geolocation_local_state.h"
 #import "ios/chrome/browser/memory/memory_debugger_manager.h"
+#import "ios/chrome/browser/metrics/ios_chrome_metrics_service_client.h"
 #include "ios/chrome/browser/net/http_server_properties_manager_factory.h"
 #include "ios/chrome/browser/pref_names.h"
 #include "ios/chrome/browser/signin/signin_manager_factory.h"
@@ -50,6 +51,7 @@ void RegisterLocalStatePrefs(PrefRegistrySimple* registry) {
   BrowserStateInfoCache::RegisterPrefs(registry);
   gcm::GCMChannelStatusSyncer::RegisterPrefs(registry);
   ios::SigninManagerFactory::RegisterPrefs(registry);
+  IOSChromeMetricsServiceClient::RegisterPrefs(registry);
   network_time::NetworkTimeTracker::RegisterPrefs(registry);
   PrefProxyConfigTrackerImpl::RegisterPrefs(registry);
   rappor::RapporService::RegisterPrefs(registry);