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

ash/display/display_manager.cc

 // Copyright (c) 2012 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 "ash/display/display_manager.h"
 
 #include <algorithm>
 #include <cmath>
 #include <limits>
 #include <map>
@@ skipping 557 matching lines @@
       origins.insert(origin);
       new_display_info_list.push_back(*iter);
     }
 
     DisplayMode new_mode;
     new_mode.size = iter->bounds_in_native().size();
     new_mode.device_scale_factor = iter->device_scale_factor();
     new_mode.ui_scale = iter->configured_ui_scale();
     const std::vector<DisplayMode>& display_modes = iter->display_modes();
     // This is empty the displays are initialized from InitFromCommandLine.
-    if (!display_modes.size())
+    if (display_modes.empty())
       continue;
     auto display_modes_iter = FindDisplayMode(*iter, new_mode);
     // Update the actual resolution selected as the resolution request may fail.
     if (display_modes_iter == display_modes.end())
       display_modes_.erase(iter->id());
     else if (display_modes_.find(iter->id()) != display_modes_.end())
       display_modes_[iter->id()] = *display_modes_iter;
   }
   if (display::Display::HasInternalDisplay() && !internal_display_connected) {
     if (display_info_.find(display::Display::InternalDisplayId()) ==
@@ skipping 745 matching lines @@
   layout.ApplyToDisplayList(display_list, updated_ids,
                             kMinimumOverlapForInvalidOffset);
 }
 
 void DisplayManager::RunPendingTasksForTest() {
   if (!software_mirroring_display_list_.empty())
     base::RunLoop().RunUntilIdle();
 }
 
 }  // namespace ash