Add a data-driven unit test to validate autofill profile merging during aggregation.

chrome/browser/autofill/personal_data_manager.h

Index: chrome/browser/autofill/personal_data_manager.h
diff --git a/chrome/browser/autofill/personal_data_manager.h b/chrome/browser/autofill/personal_data_manager.h
index dee368dae6e53cd8f9ddba91473f992893a35a93..f8bdc9944b33b37574bdd793abddd672f0c953fd 100644
--- a/chrome/browser/autofill/personal_data_manager.h
+++ b/chrome/browser/autofill/personal_data_manager.h
@@ -203,6 +203,13 @@ class PersonalDataManager
   // Saves |imported_profile| to the WebDB if it exists.
   virtual void SaveImportedProfile(const AutoFillProfile& imported_profile);
 
+  // Merges |profile| into one of the |existing_profiles| if possible; otherwise
+  // appends |profile| to the end of that list. Fills |merged_profiles| with the
+  // result.
+  bool MergeProfile(const AutoFillProfile& profile,
+                    const std::vector<AutoFillProfile*>& existing_profiles,
+                    std::vector<AutoFillProfile>* merged_profiles);
+
   // The profile hosting this PersonalDataManager.
   Profile* profile_;