[Autofill] Implement Impression metric for signin promo in CC dropdown.

components/autofill/core/browser/autofill_external_delegate.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/autofill/core/browser/autofill_external_delegate.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/i18n/case_conversion.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
+#include "base/metrics/user_metrics.h"
 #include "base/stl_util.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
 #include "components/autofill/core/browser/autocomplete_history_manager.h"
 #include "components/autofill/core/browser/autofill_driver.h"
 #include "components/autofill/core/browser/autofill_manager.h"
 #include "components/autofill/core/browser/autofill_metrics.h"
 #include "components/autofill/core/browser/popup_item_ids.h"
 #include "components/autofill/core/common/autofill_util.h"
@@ skipping 85 matching lines @@
     Suggestion separator;
     separator.frontend_id = POPUP_ITEM_ID_SEPARATOR;
     suggestions.push_back(separator);
 #endif
 
     Suggestion signin_promo_suggestion(
         l10n_util::GetStringUTF16(IDS_AUTOFILL_CREDIT_CARD_SIGNIN_PROMO));
     signin_promo_suggestion.frontend_id =
         POPUP_ITEM_ID_CREDIT_CARD_SIGNIN_PROMO;
     suggestions.push_back(signin_promo_suggestion);
+    base::RecordAction(
+        base::UserMetricsAction("Signin_Impression_FromAutofillDropdown"));
   }
 
 #if !defined(OS_ANDROID)
   // Remove the separator if it is the last element.
   DCHECK_GT(suggestions.size(), 0U);
   if (suggestions.back().frontend_id == POPUP_ITEM_ID_SEPARATOR)
     suggestions.pop_back();
 #endif
 
   // If anything else is added to modify the values after inserting the data
@@ skipping 231 matching lines @@
   suggestions->insert(suggestions->begin(), data_list_values_.size(),
                       Suggestion());
   for (size_t i = 0; i < data_list_values_.size(); i++) {
     (*suggestions)[i].value = data_list_values_[i];
     (*suggestions)[i].label = data_list_labels_[i];
     (*suggestions)[i].frontend_id = POPUP_ITEM_ID_DATALIST_ENTRY;
   }
 }
 
 }  // namespace autofill