Don't demote top match for certain match types.

chrome/browser/autocomplete/autocomplete_result.cc

Index: chrome/browser/autocomplete/autocomplete_result.cc
diff --git a/chrome/browser/autocomplete/autocomplete_result.cc b/chrome/browser/autocomplete/autocomplete_result.cc
index 0c01b3923344778c50e930e693230cfa507aa19c..8226b704aa004857ed33b5bea9d8f7a4b4f3f0a1 100644
--- a/chrome/browser/autocomplete/autocomplete_result.cc
+++ b/chrome/browser/autocomplete/autocomplete_result.cc
@@ -154,10 +154,19 @@ void AutocompleteResult::SortAndCull(const AutocompleteInput& input,
                              &AutocompleteMatch::DestinationsEqual),
                  matches_.end());
 
+  // Don't demote the top match if applicable.
+  OmniboxFieldTrial::UndemotableTopMatchTypes undemotable_top_types;
+  OmniboxFieldTrial::GetUndemotableTopTypes(input.current_page_classification(),
+                                            &undemotable_top_types);
+  const bool preserve_top_match = !matches_.empty() &&
+      (undemotable_top_types.find(matches_.begin()->type) !=

[Peter Kasting, 2013/11/05 04:09:55]

Nit: Instead of using find(), use count() and check for the result being
nonzero.

[H Fung, 2013/11/05 06:11:27]

Done.  Actually, should ContainsKey() be used instead?  I won't do it now since
I don't see it used too often and might commit this change soon.

[Peter Kasting, 2013/11/05 20:00:34]

From stl_util.h?  I don't really know why we have that -- it's not particularly
shorter, less complicated, or more efficient than using count().  We should
probably just remove that.

The only advantage I could see would be if this supports more containers than
expose count(), and thus makes code a bit more "type-agnostic" in case the
container type is changed later.

+       undemotable_top_types.end());
+
   // Sort and trim to the most relevant kMaxMatches matches.
   size_t max_num_matches = std::min(kMaxMatches, matches_.size());
   CompareWithDemoteByType comparing_object(input.current_page_classification());
-  std::sort(matches_.begin(), matches_.end(), comparing_object);
+  std::sort(preserve_top_match ? matches_.begin() + 1 : matches_.begin(),

[Peter Kasting, 2013/11/05 04:09:55]

Nit: Slightly briefer: matches.begin() + (preserve_top_match ? 1 : 0)

[H Fung, 2013/11/05 06:11:27]

Done.

+            matches_.end(), comparing_object);
   if (!matches_.empty() && !matches_.begin()->allowed_to_be_default_match &&
       OmniboxFieldTrial::ReorderForLegalDefaultMatch(
           input.current_page_classification())) {
@@ -316,6 +325,8 @@ void AutocompleteResult::AddMatch(
   DCHECK_EQ(AutocompleteMatch::SanitizeString(match.contents), match.contents);
   DCHECK_EQ(AutocompleteMatch::SanitizeString(match.description),
             match.description);
+  // GetUndemotableTopTypes() is not used here because it's done in
+  // SortAndCull(), and we depend on SortAndCull() to be called afterwards.
   CompareWithDemoteByType comparing_object(page_classification);
   ACMatches::iterator insertion_point =
       std::upper_bound(begin(), end(), match, comparing_object);