[AiS] Remove answer contents from all matches other than the first.

components/omnibox/search_provider.cc

 // Copyright 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 "components/omnibox/search_provider.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/base64.h"
@@ skipping 855 matching lines @@
   // that set a legal default match if possible.  If Instant Extended is enabled
   // and we have server-provided (and thus hopefully more accurate) scores for
   // some suggestions, we allow more of those, until we reach
   // AutocompleteResult::kMaxMatches total matches (that is, enough to fill the
   // whole popup).
   //
   // We will always return any verbatim matches, no matter how we obtained their
   // scores, unless we have already accepted AutocompleteResult::kMaxMatches
   // higher-scoring matches under the conditions above.
   std::sort(matches.begin(), matches.end(), &AutocompleteMatch::MoreRelevant);
-  matches_.clear();
+
   // Guarantee that if there's a legal default match anywhere in the result
   // set that it'll get returned.  The rotate() call does this by moving the
   // default match to the front of the list.
   ACMatches::iterator default_match = FindTopMatch(&matches);
   if (default_match != matches.end())
     std::rotate(matches.begin(), default_match, default_match + 1);
 
+  // It's possible to get a copy of an answer from previous matches and get the
+  // same or a different answer to another server-provided suggestion.  In the
+  // future we may decide that we want to have answers attached to multiple
+  // suggestions, but the current assumption is that there should only ever be
+  // one suggestion with an answer.  To maintain this assumption, remove any
+  // answers after the first.
+  RemoveExtraAnswers(&matches);
+
+  matches_.clear();
   size_t num_suggestions = 0;
   for (ACMatches::const_iterator i(matches.begin());
        (i != matches.end()) &&
            (matches_.size() < AutocompleteResult::kMaxMatches);
        ++i) {
     // SEARCH_OTHER_ENGINE is only used in the SearchProvider for the keyword
     // verbatim result, so this condition basically means "if this match is a
     // suggestion of some sort".
     if ((i->type != AutocompleteMatchType::SEARCH_WHAT_YOU_TYPED) &&
         (i->type != AutocompleteMatchType::SEARCH_OTHER_ENGINE)) {
       // If we've already hit the limit on non-server-scored suggestions, and
       // this isn't a server-scored suggestion we can add, skip it.
       if ((num_suggestions >= kMaxMatches) &&
           (!chrome::IsInstantExtendedAPIEnabled() ||
            (i->GetAdditionalInfo(kRelevanceFromServerKey) != kTrue))) {
         continue;
       }
 
       ++num_suggestions;
     }
 
     matches_.push_back(*i);
   }
   UMA_HISTOGRAM_TIMES("Omnibox.SearchProvider.ConvertResultsTime",
                       base::TimeTicks::Now() - start_time);
 }
 
+void SearchProvider::RemoveExtraAnswers(ACMatches* matches) {
+  bool answer_seen = false;
+  for (ACMatches::iterator it = matches->begin(); it != matches->end(); ++it) {
+    if (!it->answer_contents.empty()) {
+      if (!answer_seen) {
+        answer_seen = true;
+      } else {
+        it->answer_contents.clear();
+        it->answer_type.clear();
+      }
+    }
+  }
+}
+
 ACMatches::const_iterator SearchProvider::FindTopMatch() const {
   ACMatches::const_iterator it = matches_.begin();
   while ((it != matches_.end()) && !it->allowed_to_be_default_match)
     ++it;
   return it;
 }
 
 bool SearchProvider::IsTopMatchSearchWithURLInput() const {
   ACMatches::const_iterator first_match = FindTopMatch();
   return (input_.type() == metrics::OmniboxInputType::URL) &&
@@ skipping 408 matching lines @@
       match->fill_into_edit.empty())
     return;
 
   // Valid answer encountered, cache it for further queries.
   answers_cache_.UpdateRecentAnswers(match->fill_into_edit, match->answer_type);
 }
 
 void SearchProvider::DoAnswersQuery(const AutocompleteInput& input) {
   prefetch_data_ = answers_cache_.GetTopAnswerEntry(input.text());
 }