Factor out bookmark-specific sorting logic from BookmarkIndex

components/bookmarks/browser/typed_count_sorter.cc

Index: components/bookmarks/browser/typed_count_sorter.cc
diff --git a/components/bookmarks/browser/typed_count_sorter.cc b/components/bookmarks/browser/typed_count_sorter.cc
new file mode 100644
index 0000000000000000000000000000000000000000..311f13836c9253e32967967de32b26575b7f783b
--- /dev/null
+++ b/components/bookmarks/browser/typed_count_sorter.cc
@@ -0,0 +1,83 @@
+// Copyright 2016 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/bookmarks/browser/typed_count_sorter.h"
+
+#include "components/bookmarks/browser/bookmark_client.h"
+
+namespace bookmarks {
+
+using UrlTypedCountMap = BookmarkClient::UrlTypedCountMap;
+
+namespace {
+
+using UrlNodeMap = std::map<const GURL*, const TitledUrlNode*>;
+using UrlTypedCountPair = std::pair<const GURL*, int>;
+using UrlTypedCountPairs = std::vector<UrlTypedCountPair>;
+
+// Sort functor for UrlTypedCountPairs. We sort in decreasing order of typed
+// count so that the best matches will always be added to the results.
+struct UrlTypedCountPairSortFunctor {
+  bool operator()(const UrlTypedCountPair& a,
+                  const UrlTypedCountPair& b) const {
+    return a.second > b.second;
+  }
+};
+
+// Extract the GURL stored in an UrlTypedCountPair and use it to look up the
+// corresponding TitledUrlNode.
+class UrlTypedCountPairNodeLookupFunctor {
+ public:
+  UrlTypedCountPairNodeLookupFunctor(UrlNodeMap& url_node_map)
+      : url_node_map_(url_node_map) {
+  }
+
+  const TitledUrlNode* operator()(const UrlTypedCountPair& pair) const {
+    return url_node_map_[pair.first];
+  }
+
+ private:
+  UrlNodeMap& url_node_map_;
+};
+
+}  // namespace
+
+TypedCountSorter::TypedCountSorter(BookmarkClient* client)
+    : client_(client) {
+  DCHECK(client_);
+}
+
+TypedCountSorter::~TypedCountSorter() {}
+
+void TypedCountSorter::SortMatches(const TitledUrlNodeSet& matches,
+                                   TitledUrlNodes* sorted_nodes) const {
+  sorted_nodes->reserve(matches.size());
+  if (client_->SupportsTypedCountForUrls()) {
+    UrlNodeMap url_node_map;
+    UrlTypedCountMap url_typed_count_map;
+    for (auto node : matches) {
+      const GURL& url = node->GetTitledUrlNodeUrl();
+      url_node_map.insert(std::make_pair(&url, node));
+      url_typed_count_map.insert(std::make_pair(&url, 0));
+    }
+
+    client_->GetTypedCountForUrls(&url_typed_count_map);
+
+    UrlTypedCountPairs url_typed_counts;
+    std::copy(url_typed_count_map.begin(),
+              url_typed_count_map.end(),
+              std::back_inserter(url_typed_counts));
+    std::sort(url_typed_counts.begin(),
+              url_typed_counts.end(),
+              UrlTypedCountPairSortFunctor());
+    std::transform(url_typed_counts.begin(),
+                   url_typed_counts.end(),
+                   std::back_inserter(*sorted_nodes),
+                   UrlTypedCountPairNodeLookupFunctor(url_node_map));
+  } else {
+    sorted_nodes->insert(sorted_nodes->end(), matches.begin(), matches.end());
+  }
+}
+
+}  // namespace bookmarks