[AiS] Merge answers into highest-scoring result

components/omnibox/base_search_provider.cc

Index: components/omnibox/base_search_provider.cc
diff --git a/components/omnibox/base_search_provider.cc b/components/omnibox/base_search_provider.cc
index dfc26a59a207d966a01a27a120d3e35e4ece90bc..a0db8f34cb1a70471adb54d449a706455208b17e 100644
--- a/components/omnibox/base_search_provider.cc
+++ b/components/omnibox/base_search_provider.cc
@@ -420,6 +420,14 @@ void BaseSearchProvider::AddMatchToMap(
           i.first->second.RecordAdditionalInfo(kSuggestMetadataKey, metadata);
       }
     }
+    // Copy over answer data from lower-ranking item, if necessary.
+    const AutocompleteMatch& less_relevant_match =
+        i.first->second.duplicate_matches.back();

[Mark P, 2014/09/19 18:56:38]

This makes me a little nervous because you're depending that duplicate-tracking
code above always appends the latest duplicate to the end of the list.  I'm not
wedded to this idea (so if you think this behavior is obvious, you don't have to
do anything), but I think you should either:
- comment somewhere about relying on this property
- simply add another variable, MatchMap::const_iterator latest_duplicate, that
you set appropriately in either branch above, then use here.

[groby-ooo-7-16, 2014/09/22 05:49:25]

Comment added. I think it's fairly clear, but calling it out doesn't hurt. Not
sure the iterator would make it clearer. 

+    if (!less_relevant_match.answer_type.empty()) {
+      DCHECK(i.first->second.answer_type.empty());

[Mark P, 2014/09/19 18:56:38]

Why is this true?  Why can't multiple equivalent suggestions have answers
(probably the same answers)?

[groby-ooo-7-16, 2014/09/22 05:49:25]

Because suggestions are only provided by the search engine, not Chrome - and it
will only deliver one answer. The DCHECK is here to flag that necessity -
merging answers when there are two of them will be an interesting problem :)

+      i.first->second.answer_type = less_relevant_match.answer_type;
+      i.first->second.answer_contents = less_relevant_match.answer_contents;
+    }
   }
 }