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

components/autofill/core/browser/autofill_manager.h

Index: components/autofill/core/browser/autofill_manager.h
diff --git a/components/autofill/core/browser/autofill_manager.h b/components/autofill/core/browser/autofill_manager.h
index c0696cf5afa5f2489e89a9d27ca704fe63a1aa9c..af2466c2b898c65a87b8faf82d17e6a914d26273 100644
--- a/components/autofill/core/browser/autofill_manager.h
+++ b/components/autofill/core/browser/autofill_manager.h
@@ -356,6 +356,12 @@ class AutofillManager : public AutofillDownloadManager::Observer,
   // Shared code to determine if |form| should be uploaded.
   bool ShouldUploadForm(const FormStructure& form);
 
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+  // Emits a UMA metric indicating whether the accepted Autofill suggestion is
+  // from the Mac Address Book.
+  void EmitIsFromAddressBookMetric(int unique_id);
+#endif  // defined(OS_MACOSX) && !defined(OS_IOS)
+
   // Provides driver-level context to the shared code of the component. Must
   // outlive this object.
   AutofillDriver* driver_;