mac: Add histograms to measure impact of Address Book integration.

components/autofill/core/browser/autofill_external_delegate_unittest.cc

Index: components/autofill/core/browser/autofill_external_delegate_unittest.cc
diff --git a/components/autofill/core/browser/autofill_external_delegate_unittest.cc b/components/autofill/core/browser/autofill_external_delegate_unittest.cc
index e9bef0665e5e22cae944150580c6ea8e970fa972..7c9d93a4fc6471996317640b656f693d377420c2 100644
--- a/components/autofill/core/browser/autofill_external_delegate_unittest.cc
+++ b/components/autofill/core/browser/autofill_external_delegate_unittest.cc
@@ -88,6 +88,11 @@ class MockAutofillManager : public AutofillManager {
   MOCK_METHOD2(ShouldShowScanCreditCard,
                bool(const FormData& form, const FormFieldData& field));
 
+  // This method is only used for emitting histograms, but makes assumptions
+  // about the internal state of the AutofillManager. Override it to do
+  // nothing.
+  void OnUserDidAcceptAutofillSuggestion(int unique_id) override {}
+
   MOCK_METHOD5(FillOrPreviewForm,
                void(AutofillDriver::RendererFormDataAction action,
                     int query_id,