[Smart Lock] Adds UMA Metrics for actions on Account Chooser.

components/password_manager/core/browser/password_manager_metrics_util.cc

Index: components/password_manager/core/browser/password_manager_metrics_util.cc
diff --git a/components/password_manager/core/browser/password_manager_metrics_util.cc b/components/password_manager/core/browser/password_manager_metrics_util.cc
index 80cb5b39d55532eddaaddb9faf5bae6bf61dc8c8..32a0b2497a992005f7c5abce5aca8166fc90d55c 100644
--- a/components/password_manager/core/browser/password_manager_metrics_util.cc
+++ b/components/password_manager/core/browser/password_manager_metrics_util.cc
@@ -88,6 +88,12 @@ void LogAutoSigninPromoUserAction(AutoSigninPromoUserAction action) {
                             AUTO_SIGNIN_PROMO_ACTION_COUNT);
 }
 
+void LogAccountChooserUserAction(AccountChooserUserAction action) {
+  // TODO(vasilii): deprecate the histogram when the new ones hit the Stable.
+  UMA_HISTOGRAM_ENUMERATION("PasswordManager.AccountChooserDialog", action,
+                            ACCOUNT_CHOOSER_ACTION_COUNT);

[vasilii, 2016/05/25 15:18:21]

What was the reason to add this method if you have to drop it in the follow-up
patch as unused??

Note that it doesn't exist in M52 if you hoped to merge back just this CL and
not https://codereview.chromium.org/2009773003/

+}
+
 void LogAccountChooserUserActionOneAccount(AccountChooserUserAction action) {
   UMA_HISTOGRAM_ENUMERATION("PasswordManager.AccountChooserDialogOneAccount",
                             action, ACCOUNT_CHOOSER_ACTION_COUNT);