[Password Manager] Add UMA stats for custom passphrase users.

chrome/browser/password_manager/password_store_mac.cc

Index: chrome/browser/password_manager/password_store_mac.cc
diff --git a/chrome/browser/password_manager/password_store_mac.cc b/chrome/browser/password_manager/password_store_mac.cc
index 6bfc2d9c0db9e50c33becb0078f49792bb214916..ba627cc372583a0074862bc812466fe9787ca323 100644
--- a/chrome/browser/password_manager/password_store_mac.cc
+++ b/chrome/browser/password_manager/password_store_mac.cc
@@ -902,8 +902,8 @@ PasswordStoreMac::GetBackgroundTaskRunner() {
   return (thread_.get()) ? thread_->message_loop_proxy() : NULL;
 }
 
-void PasswordStoreMac::ReportMetricsImpl(const std::string& sync_username) {
-  login_metadata_db_->ReportMetrics(sync_username);
+void PasswordStoreMac::ReportMetricsImpl(PasswordManagerClient* client) {
+  login_metadata_db_->ReportMetrics(client);
 }
 
 PasswordStoreChangeList PasswordStoreMac::AddLoginImpl(