cc: Change RTree::Search to return results, add comments, more tests.

cc/base/rtree.cc

 // Copyright (c) 2015 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 "cc/base/rtree.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 91 matching lines @@
 
       DCHECK_LT(new_branch_index, current_branch);
       (*branches)[new_branch_index] = branch;
       ++new_branch_index;
     }
   }
   branches->resize(new_branch_index);
   return BuildRecursive(branches, level + 1);
 }
 
-void RTree::Search(const gfx::Rect& query, std::vector<size_t>* results) const {
+std::vector<size_t> RTree::Search(const gfx::Rect& query) const {
+  std::vector<size_t> results;
   if (num_data_elements_ > 0 && query.Intersects(root_.bounds))
-    SearchRecursive(root_.subtree, query, results);
+    SearchRecursive(root_.subtree, query, &results);
+  return results;
 }
 
 void RTree::SearchRecursive(Node* node,
                             const gfx::Rect& query,
                             std::vector<size_t>* results) const {
   for (uint16_t i = 0; i < node->num_children; ++i) {
     if (query.Intersects(node->children[i].bounds)) {
       if (node->level == 0)
         results->push_back(node->children[i].index);
       else
         SearchRecursive(node->children[i].subtree, query, results);
     }
   }
 }
 
 gfx::Rect RTree::GetBounds() const {
   return root_.bounds;
 }
 
 }  // namespace cc