Hide Night Light behind a flag

ash/ash_switches.cc

Index: ash/ash_switches.cc
diff --git a/ash/ash_switches.cc b/ash/ash_switches.cc
index 369ff26686d9dc1cac5472cec36bae65cb6ba531..30fc6c4434a4c11d56d59a5de832778694e9146e 100644
--- a/ash/ash_switches.cc
+++ b/ash/ash_switches.cc
@@ -40,6 +40,9 @@ const char kAshDisableTouchExplorationMode[] =
 const char kAshEnableMagnifierKeyScroller[] =
     "ash-enable-magnifier-key-scroller";
 
+// Enables the NightLight feature.
+const char kAshEnableNightLight[] = "ash-enable-night-light";
+
 // Enables the palette on every display, instead of only the internal one.
 const char kAshEnablePaletteOnAllDisplays[] =
     "ash-enable-palette-on-all-displays";