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

ash/display/display_manager.cc

Index: ash/display/display_manager.cc
diff --git a/ash/display/display_manager.cc b/ash/display/display_manager.cc
index 1bc2c479befce37f27d6a9f0d2bb3fc177e126f8..bed4ca47346aa40e280d4582272fafcbb3a1c4c4 100644
--- a/ash/display/display_manager.cc
+++ b/ash/display/display_manager.cc
@@ -575,7 +575,7 @@ void DisplayManager::OnNativeDisplaysChanged(
     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.