[Night Light] CL2: Ash and system tray work

ash/BUILD.gn

Index: ash/BUILD.gn
diff --git a/ash/BUILD.gn b/ash/BUILD.gn
index 059f0306a30f9ed1365f33c6b9977ee66bfa7980..5a53684b3730df5864d994d9b3e632b080deee63 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -400,6 +400,10 @@ component("ash") {
     "system/network/vpn_list_view.h",
     "system/networking_config_delegate.cc",
     "system/networking_config_delegate.h",
+    "system/night_light/night_light_controller.cc",
+    "system/night_light/night_light_controller.h",
+    "system/night_light/tray_night_light.cc",
+    "system/night_light/tray_night_light.h",
     "system/overview/overview_button_tray.cc",
     "system/overview/overview_button_tray.h",
     "system/palette/common_palette_tool.cc",
@@ -1190,6 +1194,7 @@ source_set("common_unittests") {
     "system/network/sms_observer_unittest.cc",
     "system/network/tray_network_unittest.cc",
     "system/network/vpn_list_unittest.cc",
+    "system/night_light/night_light_controller_unittest.cc",
     "system/overview/overview_button_tray_unittest.cc",
     "system/palette/mock_palette_tool_delegate.cc",
     "system/palette/mock_palette_tool_delegate.h",