Implement ScreenOrientationDelegate on ChromeOS

ash/ash.gyp

Index: ash/ash.gyp
diff --git a/ash/ash.gyp b/ash/ash.gyp
index 8a8c36edc4c8826cef872695afbf7ef84db81a98..72054d1461f7402ce8cd36ef067e0195a07abdd5 100644
--- a/ash/ash.gyp
+++ b/ash/ash.gyp
@@ -97,6 +97,8 @@
       'display/root_window_transformers.h',
       'display/screen_ash.cc',
       'display/screen_ash.h',
+      'display/screen_orientation_delegate_chromeos.cc',
+      'display/screen_orientation_delegate_chromeos.h',
       'display/screen_position_controller.cc',
       'display/screen_position_controller.h',
       'display/shared_display_edge_indicator.cc',
@@ -784,6 +786,7 @@
       'display/projecting_observer_chromeos_unittest.cc',
       'display/resolution_notification_controller_unittest.cc',
       'display/root_window_transformers_unittest.cc',
+      'display/screen_orientation_delegate_chromeos_unittest.cc',
       'display/screen_position_controller_unittest.cc',
       'drag_drop/drag_drop_controller_unittest.cc',
       'drag_drop/drag_drop_tracker_unittest.cc',
@@ -1119,6 +1122,7 @@
       'conditions': [
         ['chromeos==0', {
           'sources!': [
+            'display/screen_orientation_delegate_chromeos_unittest.cc',
             # TODO(zork): fix this test to build on Windows. See: crosbug.com/26906
             'focus_cycler_unittest.cc',
             # All tests for multiple displays: not supported on Windows Ash.