[Launcher settings] Deduplicate settings results

The settings backend can return several results with the same canonical
ID, but different display names. We want control over which of the
duplicates is selected for display when this happens, so this CL does
manual deduping rather than rely on the launcher's built-in version.

See comment in DeduplicateResults for how we choose which result to
use.

Bug: 1068851
Change-Id: I92b3ca164dd2344ba35dc1b13c7701c2935b5fde
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2213659Reviewed-by: Rachel Wong <wrong@chromium.org>
Commit-Queue: Tony Yeoman <tby@chromium.org>
Cr-Commit-Position: refs/heads/master@{#772010}

chrome/browser/ui/app_list/search/os_settings_provider.cc

@@ -50,6 +50,33 @@ void LogError(Error error) {
   UMA_HISTOGRAM_ENUMERATION("Apps.AppList.OsSettingsProvider.Error", error);
 }
 
+std::vector<SearchResultPtr> DeduplicateResults(
+    const std::vector<SearchResultPtr>& results) {
+  base::flat_map<std::string, SearchResultPtr> url_to_result;
+  for (const SearchResultPtr& result : results) {
+    const std::string url = result->url_path_with_parameters;
+    const auto it = url_to_result.find(url);
+
+    // Update a result in three cases:
+    // 1. This is the first result for its URL.
+    // 2. This has higher score than the existing result for its URL.
+    // 3. The scores are tied, but this result has more general search result
+    // type. Result types are ordered general-to-specific.
+    if (it == url_to_result.end() ||
+        result->relevance_score > it->second->relevance_score ||
+        (it->second->relevance_score == result->relevance_score &&
+         result->type < it->second->type)) {
+      url_to_result[url] = result->Clone();
+    }
+  }
+
+  std::vector<SearchResultPtr> clean_results;
+  for (const auto& pair : url_to_result) {
+    clean_results.push_back(pair.second.Clone());
+  }
+  return clean_results;
+}
+
 }  // namespace
 
 OsSettingsResult::OsSettingsResult(
@@ -136,7 +163,8 @@ void OsSettingsProvider::Start(const base::string16& query) {
 
 void OsSettingsProvider::OnSearchReturned(
     std::vector<chromeos::settings::mojom::SearchResultPtr> results) {
-  std::sort(results.begin(), results.end(),
+  std::vector<SearchResultPtr> clean_results = DeduplicateResults(results);
+  std::sort(clean_results.begin(), clean_results.end(),
             [](const SearchResultPtr& a, const SearchResultPtr& b) {
               return a->relevance_score > b->relevance_score;
             });
@@ -146,9 +174,9 @@ void OsSettingsProvider::OnSearchReturned(
   // ranking these with other results in the next version of the feature.
   SearchProvider::Results search_results;
   const int num_results =
-      std::min(static_cast<int>(results.size()), kMaxResults);
+      std::min(static_cast<int>(clean_results.size()), kMaxResults);
   for (int i = 0; i < num_results; ++i) {
-    const auto& result = results[i];
+    const auto& result = clean_results[i];
     const float score = 1.0f - i * kScoreEps;
     search_results.emplace_back(
         std::make_unique<OsSettingsResult>(profile_, result, score, icon_));