[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..c34ddec9e9be691bf02969c4e8be1c1a588e746d 100644
--- a/chrome/browser/password_manager/password_store_mac.cc
+++ b/chrome/browser/password_manager/password_store_mac.cc
@@ -875,8 +875,7 @@ PasswordStoreMac::PasswordStoreMac(
 PasswordStoreMac::~PasswordStoreMac() {}
 
 bool PasswordStoreMac::Init(
-    const syncer::SyncableService::StartSyncFlare& flare,
-    const std::string& sync_username) {
+    const syncer::SyncableService::StartSyncFlare& flare) {
   DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
   thread_.reset(new base::Thread("Chrome_PasswordStore_Thread"));
 
@@ -884,7 +883,7 @@ bool PasswordStoreMac::Init(
     thread_.reset(NULL);
     return false;
   }
-  return password_manager::PasswordStore::Init(flare, sync_username);
+  return password_manager::PasswordStore::Init(flare);
 }
 
 void PasswordStoreMac::Shutdown() {
@@ -902,8 +901,9 @@ 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(
+    password_manager::PasswordManagerClient* client) {
+  login_metadata_db_->ReportMetrics(client);
 }
 
 PasswordStoreChangeList PasswordStoreMac::AddLoginImpl(