Use emplace_back in RTree::Build

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>
 #include <cmath>
 
 #include "base/logging.h"
 #include "base/numerics/saturated_arithmetic.h"
 
 namespace cc {
 
 RTree::RTree() : num_data_elements_(0u) {}
 
 RTree::~RTree() {}
 
 RTree::Node* RTree::AllocateNodeAtLevel(int level) {
   // We don't allow reallocations, since that would invalidate references to
   // existing nodes, so verify that capacity > size.
   DCHECK_GT(nodes_.capacity(), nodes_.size());
-  nodes_.emplace_back();
-  Node& node = nodes_.back();
-  node.num_children = 0;
-  node.level = level;
-  return &node;
+  nodes_.emplace_back(level);
+  return &nodes_.back();
 }
 
 RTree::Branch RTree::BuildRecursive(std::vector<Branch>* branches, int level) {
   // Only one branch.  It will be the root.
   if (branches->size() == 1)
     return (*branches)[0];
 
   // TODO(vmpstr): Investigate if branches should be sorted in y.
   // The comment from Skia reads:
   // We might sort our branches here, but we expect Blink gives us a reasonable
@@ skipping 87 matching lines @@
         SearchRecursive(node->children[i].subtree, query, results);
     }
   }
 }
 
 gfx::Rect RTree::GetBounds() const {
   return root_.bounds;
 }
 
 }  // namespace cc