[AiS] Add a new AutocompleteMatchType for Answers in Suggest.

chrome/browser/autocomplete/base_search_provider.cc

Index: chrome/browser/autocomplete/base_search_provider.cc
diff --git a/chrome/browser/autocomplete/base_search_provider.cc b/chrome/browser/autocomplete/base_search_provider.cc
index 3de7d4126c3641dfdc2d2311144f8c5b075dbc26..cf0ca1d9213ad0eb42165ba2c263b63988f8360b 100644
--- a/chrome/browser/autocomplete/base_search_provider.cc
+++ b/chrome/browser/autocomplete/base_search_provider.cc
@@ -915,6 +915,7 @@ bool BaseSearchProvider::ParseSuggestResults(const base::Value& root_val,
           // Extract Answers, if provided.
           const base::DictionaryValue* answer_json = NULL;
           if (suggestion_detail->GetDictionary("ansa", &answer_json)) {
+            match_type = AutocompleteMatchType::SEARCH_SUGGEST_ANSWER;

[Peter Kasting, 2014/06/10 21:49:46]

My only concern here would be if there's a validation issue, where if we don't
get "correct" data from the ansa/ansb parameters (or whatever), some later stage
will auto-downgrade this match to appear like a normal search result or
something.  If that could ever happen, we should ensure it happens here so we
tag the match type correctly for what the user will actually see.

[Justin Donnelly, 2014/06/11 15:51:53]

Good question, but no we don't plan to downgrade answers.  If the JSON is
missing required data or malformed, we're going to drop the answer altogether. 
(The current frontend code does, in fact downgrade but my next CL is going to
change this.)

             std::string contents;
             base::JSONWriter::Write(answer_json, &contents);
             answer_contents = base::UTF8ToUTF16(contents);