dark_mode: Follow up to keep old colors.

Bug: 1133952
Change-Id: I843e304131eea6f120be6f32f00b427d1f6477df
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2444453Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813046}

ash/style/ash_color_provider.cc

@@ -7,6 +7,7 @@
 #include <math.h>
 
 #include "ash/public/cpp/ash_constants.h"
+#include "ash/public/cpp/ash_features.h"
 #include "ash/public/cpp/ash_pref_names.h"
 #include "ash/public/cpp/login_constants.h"
 #include "ash/session/session_controller_impl.h"
@@ -331,7 +332,7 @@ void AshColorProvider::RemoveObserver(ColorModeObserver* observer) {
 }
 
 bool AshColorProvider::IsDarkModeEnabled() const {
-  if (override_light_mode_as_default_)
+  if (!features::IsDarkLightModeEnabled() && override_light_mode_as_default_)
     return false;
 
   if (!active_user_pref_service_)

ash/style/ash_color_provider.h

@@ -233,8 +233,9 @@ class ASH_EXPORT AshColorProvider : public SessionObserver {
   // Default color mode is dark, which is controlled by pref |kDarkModeEnabled|
   // currently. But we can also override it to light through
   // ScopedLightModeAsDefault. This is done to help keeping some of the UI
-  // elements as light by default before launching dark/light mode. This will be
-  // removed once enabling dark/light mode.
+  // elements as light by default before launching dark/light mode. Overriding
+  // only if the kDarkLightMode feature is disabled. This variable will be
+  // removed once enabled dark/light mode.
   bool override_light_mode_as_default_ = false;
 
   base::ObserverList<ColorModeObserver> observers_;

ash/style/scoped_light_mode_as_default.h

@@ -10,7 +10,8 @@ namespace ash {
 // A helper class to set default color mode to light. Color mode is dark by
 // default, which is controlled by pref |kDarkModeEnabled| currently. Some of
 // the components need to be kept as LIGHT by default before launching
-// dark/light mode. E.g. power button menu and system toast.
+// dark/light mode. E.g. power button menu and system toast. Overriding only if
+// the kDarkLightMode feature is disabled.
 class ScopedLightModeAsDefault {
  public:
   ScopedLightModeAsDefault();