[Autofill] Add UMA timing metrics for requestAutocomplete dialog.

chrome/browser/autofill/autocheckout_manager.cc

Index: chrome/browser/autofill/autocheckout_manager.cc
diff --git a/chrome/browser/autofill/autocheckout_manager.cc b/chrome/browser/autofill/autocheckout_manager.cc
index 7504399def346aad8c5d13e89fb01616a4b16e2b..452ad72122f616b3ba3ae214bde668eb83c6311b 100644
--- a/chrome/browser/autofill/autocheckout_manager.cc
+++ b/chrome/browser/autofill/autocheckout_manager.cc
@@ -54,6 +54,8 @@ FormData BuildAutocheckoutFormData() {
 
 }  // namespace
 
+namespace autofill {
+
 AutocheckoutManager::AutocheckoutManager(AutofillManager* autofill_manager)
     : autofill_manager_(autofill_manager),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)) {
@@ -69,10 +71,13 @@ void AutocheckoutManager::ShowAutocheckoutDialog(
       base::Bind(&AutocheckoutManager::ReturnAutocheckoutData,
                  weak_ptr_factory_.GetWeakPtr());
   autofill_manager_->ShowRequestAutocompleteDialog(
-      BuildAutocheckoutFormData(), frame_url, ssl_status, callback);
+      BuildAutocheckoutFormData(), frame_url, ssl_status,
+      AUTOCOMPLETE_DIALOG_REQUESTER_AUTOCHECKOUT, callback);
 }
 
 void AutocheckoutManager::ReturnAutocheckoutData(const FormStructure* result) {
   // TODO(ramankk): Parse the response FormStructure.
   autofill_manager_->RequestAutocompleteDialogClosed();
 }
+
+}  // namespace autofill