aura: Replace UI-feature GYP flags with switches.

ash/wm/power_button_controller.h

Index: ash/wm/power_button_controller.h
diff --git a/ash/wm/power_button_controller.h b/ash/wm/power_button_controller.h
index 00a15076f43218b76e6c581f0faa5c84e6424c7b..b25f0a1b1310ef8a487ed6d2d91d9b70e4f11dfb 100644
--- a/ash/wm/power_button_controller.h
+++ b/ash/wm/power_button_controller.h
@@ -132,6 +132,10 @@ class ASH_EXPORT PowerButtonController : public aura::RootWindowObserver {
     delegate_.reset(delegate);
   }
 
+  void set_has_legacy_power_button_for_test(bool legacy) {
+    has_legacy_power_button_ = legacy;
+  }
+
   // Called when the user logs in.
   void OnLoginStateChange(bool logged_in, bool is_guest);
 
@@ -195,6 +199,10 @@ class ASH_EXPORT PowerButtonController : public aura::RootWindowObserver {
   // screen has been locked?
   bool should_start_shutdown_timer_after_lock_;
 
+  // Was a command-line switch set telling us that we're running on hardware
+  // that misreports power button releases?
+  bool has_legacy_power_button_;
+
   // Responsible for painting |background_layer_|.
   scoped_ptr<BackgroundLayerDelegate> background_layer_delegate_;