Omnibox: Make the Controller Reorder Matches for Inlining

chrome/browser/autocomplete/autocomplete_result.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/autocomplete/autocomplete_result.h"
 
 #include <algorithm>
 #include <iterator>
 
 #include "base/logging.h"
@@ skipping 138 matching lines @@
   // Remove duplicates.
   std::sort(matches_.begin(), matches_.end(),
             &AutocompleteMatch::DestinationSortFunc);
   matches_.erase(std::unique(matches_.begin(), matches_.end(),
                              &AutocompleteMatch::DestinationsEqual),
                  matches_.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::partial_sort(matches_.begin(), matches_.begin() + max_num_matches,
-                    matches_.end(), comparing_object);
+  std::sort(matches_.begin(), matches_.end(), comparing_object);
+  if (!matches_.empty() && !matches_.begin()->allowed_to_be_default_match &&
+      OmniboxFieldTrial::ReorderForLegalDefaultMatch(
+          input.current_page_classification())) {
+    // Top match is not allowed to be the default match.  Find the most
+    // relevant legal match and shift it to the front.
+    for (AutocompleteResult::iterator it = matches_.begin() + 1;
+         it != matches_.end(); ++it) {
+      if (it->allowed_to_be_default_match) {
+        std::rotate(matches_.begin(), it, it + 1);
+        break;
+      }
+    }
+  }
   // In the process of trimming, drop all matches with a demoted relevance
   // score of 0.
   size_t num_matches;
   for (num_matches = 0u; (num_matches < max_num_matches) &&
        (comparing_object.GetDemotedRelevance(*match_at(num_matches)) > 0);
        ++num_matches) {}
   matches_.resize(num_matches);
 
-  default_match_ = begin();
+  default_match_ = matches_.begin();
+  DCHECK((default_match_ == matches_.end()) ||
+      default_match_->allowed_to_be_default_match);
 
   // Set the alternate nav URL.
-  alternate_nav_url_ = (default_match_ == end()) ?
+  alternate_nav_url_ = (default_match_ == matches_.end()) ?
       GURL() : ComputeAlternateNavUrl(input, *default_match_);
 }
 
 bool AutocompleteResult::HasCopiedMatches() const {
   for (ACMatches::const_iterator i(begin()); i != end(); ++i) {
     if (i->from_previous)
       return true;
   }
   return false;
 }
@@ skipping 150 matching lines @@
        i != old_matches.rend() && delta > 0; ++i) {
     if (!HasMatchByDestination(*i, new_matches)) {
       AutocompleteMatch match = *i;
       match.relevance = std::min(max_relevance, match.relevance);
       match.from_previous = true;
       AddMatch(page_classification, match);
       delta--;
     }
   }
 }