[Autofill] Deduplicate Autocomplete and Datalist suggestions, keeping the latter

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 91 matching lines @@
 
   // Handle applying any Autofill warnings to the Autofill popup.
   void ApplyAutofillWarnings(std::vector<Suggestion>* suggestions);
 
   // Handle applying any Autofill option listings to the Autofill popup.
   // This function should only get called when there is at least one
   // multi-field suggestion in the list of suggestions.
   void ApplyAutofillOptions(std::vector<Suggestion>* suggestions);
 
   // Insert the data list values at the start of the given list, including
-  // any required separators.
+  // any required separators. Will also go through |suggestions| and remove
+  // duplicate autocomplete (not Autofill) suggestions, keeping their datalist
+  // version.
   void InsertDataListValues(std::vector<Suggestion>* suggestions);
 
   AutofillManager* manager_;  // weak.
 
   // Provides driver-level context to the shared code of the component. Must
   // outlive this object.
   AutofillDriver* driver_;  // weak
 
   // The ID of the last request sent for form field Autofill.  Used to ignore
   // out of date responses.
@@ skipping 25 matching lines @@
   std::vector<base::string16> data_list_labels_;
 
   base::WeakPtrFactory<AutofillExternalDelegate> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AutofillExternalDelegate);
 };
 
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CORE_BROWSER_AUTOFILL_EXTERNAL_DELEGATE_H_