Add histogram for "scan credit card" usage.

components/autofill/core/browser/autofill_external_delegate.h

 // 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.
 
 #ifndef COMPONENTS_AUTOFILL_CORE_BROWSER_AUTOFILL_EXTERNAL_DELEGATE_H_
 #define COMPONENTS_AUTOFILL_CORE_BROWSER_AUTOFILL_EXTERNAL_DELEGATE_H_
 
 #include <vector>
 
 #include "base/compiler_specific.h"
@@ skipping 135 matching lines @@
   // Should we display a warning if Autofill is disabled?
   bool display_warning_if_disabled_;
 
   // Does the popup include any Autofill profile or credit card suggestions?
   bool has_suggestion_;
 
   // Have we already shown Autofill suggestions for the field the user is
   // currently editing?  Used to keep track of state for metrics logging.
   bool has_shown_popup_for_current_edit_;
 
+  // FIXME

[Justin Donnelly, 2015/11/16 20:23:28]

Just noticed this. I assume you meant to add a comment here?

[Evan Stade, 2015/11/16 20:43:53]

oops. Yes, that was the intent.

+  bool should_show_scan_credit_card_;
+
+  // Whether the access Address Book prompt has ever been shown for the current
+  // |query_form_|. This variable is only used on OSX.
+  bool has_shown_address_book_prompt;
+
   // The current data list values.
   std::vector<base::string16> data_list_values_;
   std::vector<base::string16> data_list_labels_;
 
-  // Whether the access Address Book prompt has ever been shown for the current
-  // |query_form_|. This variable is only used on OSX.
-  bool has_shown_address_book_prompt;
-
   base::WeakPtrFactory<AutofillExternalDelegate> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AutofillExternalDelegate);
 };
 
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_AUTOFILL_EXTERNAL_DELEGATE_H_