Intorduce PowerButtonObserver API

athena/athena.gyp

Index: athena/athena.gyp
diff --git a/athena/athena.gyp b/athena/athena.gyp
index e3bddc3eccffeb97c02003b22bf13590140fde33..ee2f614f827aaf073c76d2e71c9b1f1d8d3d82b7 100644
--- a/athena/athena.gyp
+++ b/athena/athena.gyp
@@ -69,6 +69,9 @@
         'input/accelerator_manager_impl.cc',
         'input/accelerator_manager_impl.h',
         'input/input_manager_impl.cc',
+        'input/input_manager_impl.h',
+        'input/power_button_controller.cc',
+        'input/power_button_controller.h',
         'input/public/accelerator_manager.h',
         'input/public/input_manager.h',
         'resource_manager/delegate/resource_manager_delegate.cc',
@@ -87,8 +90,8 @@
         'system/network_selector.h',
         'system/orientation_controller.cc',
         'system/orientation_controller.h',
-        'system/power_button_controller.cc',
-        'system/power_button_controller.h',
+        'system/shutdown_dialog.cc',
+        'system/shutdown_dialog.h',
         'system/status_icon_container_view.cc',
         'system/status_icon_container_view.h',
         'system/time_view.cc',
@@ -289,6 +292,7 @@
         'home/home_card_gesture_manager_unittest.cc',
         'home/home_card_unittest.cc',
         'input/accelerator_manager_unittest.cc',
+        'input/input_manager_unittest.cc',
         'resource_manager/memory_pressure_notifier_unittest.cc',
         'resource_manager/resource_manager_unittest.cc',
         'screen/screen_manager_unittest.cc',