app_list search results relevance scores are clamped to [0, 1] range.

ui/app_list/search/mixer.cc

 // Copyright 2013 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 "ui/app_list/search/mixer.h"
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <string>
@@ skipping 44 matching lines @@
       : max_results_(max_results), boost_(boost) {}
   ~Group() {}
 
   void AddProvider(SearchProvider* provider) { providers_.push_back(provider); }
 
   void FetchResults(bool is_voice_query, const KnownResults& known_results) {
     results_.clear();
 
     for (const SearchProvider* provider : providers_) {
       for (SearchResult* result : provider->results()) {
-        DCHECK_GE(result->relevance(), 0.0);
-        DCHECK_LE(result->relevance(), 1.0);
         DCHECK(!result->id().empty());
 
+        // We cannot rely on providers to give relevance scores in the range
+        // [0.0, 1.0] (e.g., PeopleProvider directly gives values from the
+        // Google+ API). Clamp to that range.
+        double relevance = std::min(std::max(result->relevance(), 0.0), 1.0);
+
         double boost = boost_;
         KnownResults::const_iterator known_it =
             known_results.find(result->id());
         if (known_it != known_results.end()) {
           switch (known_it->second) {
             case PERFECT_PRIMARY:
               boost = 4.0;
               break;
             case PREFIX_PRIMARY:
               boost = 3.75;
               break;
             case PERFECT_SECONDARY:
               boost = 3.25;
               break;
             case PREFIX_SECONDARY:
               boost = 3.0;
               break;
             case UNKNOWN_RESULT:
               NOTREACHED() << "Unknown result in KnownResults?";
               break;
           }
         }
 
         // If this is a voice query, voice results receive a massive boost.
         if (is_voice_query && result->voice_result())
           boost += 4.0;
 
-        results_.push_back(SortData(result, result->relevance() + boost));
+        results_.push_back(SortData(result, relevance + boost));
       }
     }
 
     std::sort(results_.begin(), results_.end());
     if (max_results_ != kNoMaxResultsLimit && results_.size() > max_results_)
       results_.resize(max_results_);
   }
 
   const SortedResults& results() const { return results_; }
 
@@ skipping 136 matching lines @@
   results->swap(final);
 }
 
 void Mixer::FetchResults(bool is_voice_query,
                          const KnownResults& known_results) {
   for (const auto& item : groups_)
     item.second->FetchResults(is_voice_query, known_results);
 }
 
 }  // namespace app_list