dark_mode: Hook up with Chrome browser's dark mode.

Bug: 1145699
Change-Id: I5b9db0b6776b26ede2687cbc2d5d63702eb0bc70
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521831Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825102}

ash/style/ash_color_provider.cc

@@ -168,6 +168,14 @@ void AshColorProvider::OnActiveUserPrefServiceChanged(PrefService* prefs) {
   NotifyColorModeThemedPrefChange();
 }
 
+void AshColorProvider::OnSessionStateChanged(
+    session_manager::SessionState state) {
+  if (!features::IsDarkLightModeEnabled())
+    return;
+  ui::NativeTheme::GetInstanceForNativeUi()->set_use_dark_colors(
+      IsDarkModeEnabled());
+}
+
 SkColor AshColorProvider::GetShieldLayerColor(ShieldLayerType type) const {
   constexpr int kAlphas[] = {kAlpha20, kAlpha40, kAlpha60, kAlpha80, kAlpha90};
   DCHECK_LT(static_cast<size_t>(type), base::size(kAlphas));
@@ -366,6 +374,9 @@ void AshColorProvider::ToggleColorMode() {
                                         !IsDarkModeEnabled());
   active_user_pref_service_->CommitPendingWrite();
 
+  ui::NativeTheme::GetInstanceForNativeUi()->set_use_dark_colors(
+      IsDarkModeEnabled());
+
   AttemptRestartChrome();
 }
 

ash/style/ash_color_provider.h

@@ -158,6 +158,7 @@ class ASH_EXPORT AshColorProvider : public SessionObserver {
 
   // SessionObserver:
   void OnActiveUserPrefServiceChanged(PrefService* prefs) override;
+  void OnSessionStateChanged(session_manager::SessionState state) override;
 
   SkColor GetShieldLayerColor(ShieldLayerType type) const;
   SkColor GetBaseLayerColor(BaseLayerType type) const;