Use container::back() and container::pop_back().

cc/surfaces/surface_manager.cc

 // Copyright 2014 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/surfaces/surface_manager.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/logging.h"
@@ skipping 286 matching lines @@
   // of unregistering the hierarchy first before either of them.
   DCHECK_EQ(namespace_client_map_.count(parent_namespace), 1u);
 
   auto iter = namespace_client_map_.find(parent_namespace);
 
   std::vector<uint32_t>& children = iter->second.children;
   bool found_child = false;
   for (size_t i = 0; i < children.size(); ++i) {
     if (children[i] == child_namespace) {
       found_child = true;
-      children[i] = children[children.size() - 1];
+      children[i] = children.back();
       children.resize(children.size() - 1);
       break;
     }
   }
   DCHECK(found_child);
 
   // The SurfaceFactoryClient and hierarchy can be registered/unregistered
   // in either order, so empty namespace_client_map entries need to be
   // checked when removing either clients or relationships.
   if (iter->second.is_empty()) {
@@ skipping 23 matching lines @@
 
 bool SurfaceManager::SurfaceModified(SurfaceId surface_id) {
   CHECK(thread_checker_.CalledOnValidThread());
   bool changed = false;
   FOR_EACH_OBSERVER(SurfaceDamageObserver, observer_list_,
                     OnSurfaceDamaged(surface_id, &changed));
   return changed;
 }
 
 }  // namespace cc