Add histogram for "scan credit card" usage.

components/autofill/core/browser/autofill_manager.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_MANAGER_H_
 #define COMPONENTS_AUTOFILL_CORE_BROWSER_AUTOFILL_MANAGER_H_
 
 #include <list>
 #include <map>
 #include <string>
@@ skipping 82 matching lines @@
   bool AccessAddressBook();
 
   // The access Address Book prompt was shown for a form.
   void ShowedAccessAddressBookPrompt();
 
   // The number of times that the access address book prompt was shown.
   int AccessAddressBookPromptCount();
 #endif  // defined(OS_MACOSX) && !defined(OS_IOS)
 
   // Whether the |field| should show an entry to scan a credit card.
-  bool ShouldShowScanCreditCard(const FormData& form,
-                                const FormFieldData& field);
+  virtual bool ShouldShowScanCreditCard(const FormData& form,
+                                        const FormFieldData& field);
 
   // Called from our external delegate so they cannot be private.
   virtual void FillOrPreviewForm(AutofillDriver::RendererFormDataAction action,
                                  int query_id,
                                  const FormData& form,
                                  const FormFieldData& field,
                                  int unique_id);
   virtual void FillCreditCardForm(int query_id,
                                   const FormData& form,
                                   const FormFieldData& field,
@@ skipping 283 matching lines @@
   FRIEND_TEST_ALL_PREFIXES(AutofillManagerTest,
                            AutocompleteOffRespected);
   FRIEND_TEST_ALL_PREFIXES(AutofillManagerTest,
                            AutocompleteOffRespectedWithFlag);
   DISALLOW_COPY_AND_ASSIGN(AutofillManager);
 };
 
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_AUTOFILL_MANAGER_H_