[Cleanup] fix macro, comments and unused includes

ash/root_window_settings.cc

Index: ash/root_window_settings.cc
diff --git a/ash/root_window_settings.cc b/ash/root_window_settings.cc
index a5e396898446738ae141cacd575481ea99b55caa..06198ca1562fb03573e0762f4498211d3b7b5306 100644
--- a/ash/root_window_settings.cc
+++ b/ash/root_window_settings.cc
@@ -23,9 +23,9 @@ RootWindowSettings::RootWindowSettings()
 }
 
 RootWindowSettings* InitRootWindowSettings(aura::RootWindow* root) {
-  RootWindowSettings* property = new RootWindowSettings();
-  root->SetProperty(kRootWindowSettingsKey, property);
-  return property;
+  RootWindowSettings* settings = new RootWindowSettings();
+  root->SetProperty(kRootWindowSettingsKey, settings);
+  return settings;
 }
 
 RootWindowSettings* GetRootWindowSettings(aura::RootWindow* root) {