[Autofill] Add UMA timing metrics for requestAutocomplete dialog.

chrome/browser/autofill/autocheckout_infobar_delegate.cc

Index: chrome/browser/autofill/autocheckout_infobar_delegate.cc
diff --git a/chrome/browser/autofill/autocheckout_infobar_delegate.cc b/chrome/browser/autofill/autocheckout_infobar_delegate.cc
index b23b2e0a937e12a7dbd9945cee77df972c1c1cc2..8c1ddd756a52a387c468938d119ed671b5e4cf39 100644
--- a/chrome/browser/autofill/autocheckout_infobar_delegate.cc
+++ b/chrome/browser/autofill/autocheckout_infobar_delegate.cc
@@ -17,6 +17,8 @@
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/base/resource/resource_bundle.h"
 
+namespace autofill {
+
 // static
 void AutocheckoutInfoBarDelegate::Create(
     const AutofillMetrics& metric_logger,
@@ -116,3 +118,4 @@ bool AutocheckoutInfoBarDelegate::LinkClicked(
   return false;
 }
 
+}  // namespace autofill