dark_mode: Syncable dark/light mode switcher.

Add the logic for syncable dark/light switcher. Enable/Disable the dark
mode through the feature pod in system tray will update the preference
for this user on other devices too.
Login screen will be done in a follow up cl.

Bug: 1106012
Change-Id: Idbbc3f5652effdc7590713fc5687e031e3d97dac
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2373134
Commit-Queue: Min Chen <minch@chromium.org>
Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802737}

ash/BUILD.gn

@@ -903,6 +903,7 @@ component("ash") {
     "system/cast/tray_cast.h",
     "system/cast/unified_cast_detailed_view_controller.cc",
     "system/cast/unified_cast_detailed_view_controller.h",
+    "system/dark_mode/color_mode_observer.h",
     "system/dark_mode/dark_mode_detailed_view.cc",
     "system/dark_mode/dark_mode_detailed_view.h",
     "system/dark_mode/dark_mode_detailed_view_controller.cc",

ash/ash_prefs.cc

@@ -20,6 +20,7 @@
 #include "ash/public/cpp/ash_pref_names.h"
 #include "ash/shelf/contextual_tooltip.h"
 #include "ash/shelf/shelf_controller.h"
+#include "ash/style/ash_color_provider.h"
 #include "ash/system/bluetooth/bluetooth_power_controller.h"
 #include "ash/system/caps_lock_notification_controller.h"
 #include "ash/system/gesture_education/gesture_education_notification_controller.h"
@@ -47,6 +48,7 @@ void RegisterProfilePrefs(PrefRegistrySimple* registry, bool for_test) {
   AccessibilityControllerImpl::RegisterProfilePrefs(registry);
   AppListControllerImpl::RegisterProfilePrefs(registry);
   AssistantControllerImpl::RegisterProfilePrefs(registry);
+  AshColorProvider::RegisterProfilePrefs(registry);
   AmbientController::RegisterProfilePrefs(registry);
   BluetoothPowerController::RegisterProfilePrefs(registry);
   CapsLockNotificationController::RegisterProfilePrefs(registry, for_test);

ash/public/cpp/ash_constants.h

@@ -72,6 +72,9 @@ constexpr SkColor kDefaultFrameColor = SkColorSetRGB(0xFD, 0xFE, 0xFF);
 // Whether keyboard auto repeat is enabled by default.
 constexpr bool kDefaultKeyAutoRepeatEnabled = true;
 
+// Whether dark mode is enabled by default.
+constexpr bool kDefaultDarkModeEnabled = true;
+
 // The default delay before a held keypress will start to auto repeat.
 constexpr base::TimeDelta kDefaultKeyAutoRepeatDelay =
     base::TimeDelta::FromMilliseconds(500);

ash/public/cpp/ash_pref_names.cc

@@ -577,6 +577,9 @@ const char kMouseReverseScroll[] = "settings.mouse.reverse_scroll";
 // contextual nudge was shown.
 const char kMultipasteNudges[] = "ash.clipboard.multipaste_nudges";
 
+// A boolean pref that indicates whether dark mode is enabled.
+const char kDarkModeEnabled[] = "cros.system.dark_mode_enabled";
+
 // NOTE: New prefs should start with the "ash." prefix. Existing prefs moved
 // into this file should not be renamed, since they may be synced.
 

ash/public/cpp/ash_pref_names.h

@@ -207,6 +207,8 @@ ASH_PUBLIC_EXPORT extern const char kMouseReverseScroll[];
 
 ASH_PUBLIC_EXPORT extern const char kMultipasteNudges[];
 
+ASH_PUBLIC_EXPORT extern const char kDarkModeEnabled[];
+
 }  // namespace prefs
 
 }  // namespace ash

ash/shelf/shelf_config.cc

@@ -494,10 +494,9 @@ AshColorProvider::BaseLayerType ShelfConfig::GetShelfBaseLayerType() const {
 
   if (in_tablet_mode_) {
     if (is_in_app()) {
-      return AshColorProvider::Get()->color_mode() ==
-                     AshColorProvider::AshColorMode::kLight
-                 ? AshColorProvider::BaseLayerType::kOpaque
-                 : AshColorProvider::BaseLayerType::kTransparent90;
+      return AshColorProvider::Get()->IsDarkModeEnabled()
+                 ? AshColorProvider::BaseLayerType::kTransparent90
+                 : AshColorProvider::BaseLayerType::kOpaque;
     }
     return AshColorProvider::BaseLayerType::kTransparent60;
   }

ash/shell.cc

@@ -548,7 +548,6 @@ Shell::Shell(std::unique_ptr<ShellDelegate> shell_delegate)
           std::make_unique<KeyboardBrightnessController>()),
       locale_update_controller_(std::make_unique<LocaleUpdateControllerImpl>()),
       parent_access_controller_(std::make_unique<ParentAccessController>()),
-      ash_color_provider_(std::make_unique<AshColorProvider>()),
       session_controller_(std::make_unique<SessionControllerImpl>()),
       shell_delegate_(std::move(shell_delegate)),
       shutdown_controller_(std::make_unique<ShutdownControllerImpl>()),
@@ -958,6 +957,8 @@ void Shell::Init(
   if (context_factory)
     env->set_context_factory(context_factory);
 
+  ash_color_provider_ = std::make_unique<AshColorProvider>();
+
   // Night Light depends on the display manager, the display color manager, and
   // aura::Env, so initialize it after all have been initialized.
   night_light_controller_ = std::make_unique<NightLightControllerImpl>();

ash/shell.h

@@ -697,8 +697,8 @@ class ASH_EXPORT Shell : public SessionObserver,
   std::unique_ptr<ParentAccessController> parent_access_controller_;
   std::unique_ptr<QuickAnswersController> quick_answers_controller_;
   std::unique_ptr<ResizeShadowController> resize_shadow_controller_;
-  std::unique_ptr<AshColorProvider> ash_color_provider_;
   std::unique_ptr<SessionControllerImpl> session_controller_;
+  std::unique_ptr<AshColorProvider> ash_color_provider_;
   std::unique_ptr<NightLightControllerImpl> night_light_controller_;
   std::unique_ptr<PrivacyScreenController> privacy_screen_controller_;
   std::unique_ptr<PolicyRecommendationRestorer> policy_recommendation_restorer_;

ash/style/ash_color_provider.cc

@@ -6,11 +6,19 @@
 
 #include <math.h>
 
+#include "ash/public/cpp/ash_constants.h"
+#include "ash/public/cpp/ash_pref_names.h"
+#include "ash/session/session_controller_impl.h"
 #include "ash/shell.h"
+#include "ash/system/dark_mode/color_mode_observer.h"
 #include "ash/wallpaper/wallpaper_controller_impl.h"
+#include "base/bind.h"
 #include "base/check_op.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
+#include "components/pref_registry/pref_registry_syncable.h"
+#include "components/prefs/pref_change_registrar.h"
+#include "components/prefs/pref_service.h"
 #include "ui/chromeos/colors/cros_colors.h"
 #include "ui/gfx/color_analysis.h"
 #include "ui/gfx/color_palette.h"
@@ -61,6 +69,14 @@ bool IsLightMode(AshColorProvider::AshColorMode color_mode) {
 
 }  // namespace
 
+AshColorProvider::AshColorProvider() {
+  Shell::Get()->session_controller()->AddObserver(this);
+}
+
+AshColorProvider::~AshColorProvider() {
+  Shell::Get()->session_controller()->RemoveObserver(this);
+}
+
 // static
 AshColorProvider* AshColorProvider::Get() {
   return Shell::Get()->ash_color_provider();
@@ -79,6 +95,27 @@ SkColor AshColorProvider::GetSecondToneColor(SkColor color_of_first_tone) {
       std::round(SkColorGetA(color_of_first_tone) * kSecondToneOpacity));
 }
 
+// static
+void AshColorProvider::RegisterProfilePrefs(PrefRegistrySimple* registry) {
+  registry->RegisterBooleanPref(
+      prefs::kDarkModeEnabled, kDefaultDarkModeEnabled,
+      user_prefs::PrefRegistrySyncable::SYNCABLE_OS_PREF);
+}
+
+void AshColorProvider::OnActiveUserPrefServiceChanged(PrefService* prefs) {
+  active_user_pref_service_ = prefs;
+  pref_change_registrar_ = std::make_unique<PrefChangeRegistrar>();
+  pref_change_registrar_->Init(prefs);
+
+  pref_change_registrar_->Add(
+      prefs::kDarkModeEnabled,
+      base::BindRepeating(&AshColorProvider::NotifyDarkModeEnabledPrefChange,
+                          base::Unretained(this)));
+
+  // Immediately tell all the observers to load this user's saved preferences.
+  NotifyDarkModeEnabledPrefChange();
+}
+
 SkColor AshColorProvider::DeprecatedGetShieldLayerColor(
     ShieldLayerType type,
     SkColor default_color) const {
@@ -218,6 +255,27 @@ void AshColorProvider::DecorateCloseButton(views::ImageButton* button,
   // added separately so its easier to monitor performance.
 }
 
+void AshColorProvider::AddObserver(ColorModeObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void AshColorProvider::RemoveObserver(ColorModeObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
+bool AshColorProvider::IsDarkModeEnabled() const {
+  if (!active_user_pref_service_)
+    return kDefaultDarkModeEnabled;
+  return active_user_pref_service_->GetBoolean(prefs::kDarkModeEnabled);
+}
+
+void AshColorProvider::Toggle() {
+  DCHECK(active_user_pref_service_);
+  active_user_pref_service_->SetBoolean(prefs::kDarkModeEnabled,
+                                        !IsDarkModeEnabled());
+  active_user_pref_service_->CommitPendingWrite();
+}
+
 SkColor AshColorProvider::GetShieldLayerColorImpl(
     ShieldLayerType type,
     AshColorMode color_mode) const {
@@ -394,4 +452,10 @@ SkColor AshColorProvider::GetBackgroundThemedColor(
       muted_color);
 }
 
+void AshColorProvider::NotifyDarkModeEnabledPrefChange() {
+  const bool is_enabled = IsDarkModeEnabled();
+  for (auto& observer : observers_)
+    observer.OnColorModeChanged(is_enabled);
+}
+
 }  // namespace ash

ash/style/ash_color_provider.h

@@ -6,15 +6,22 @@
 #define ASH_STYLE_ASH_COLOR_PROVIDER_H_
 
 #include "ash/ash_export.h"
+#include "ash/public/cpp/session/session_observer.h"
+#include "base/observer_list.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/vector_icon_types.h"
 
+class PrefChangeRegistrar;
+class PrefRegistrySimple;
+class PrefService;
+
 namespace views {
 class ImageButton;
 class LabelButton;
 }  // namespace views
 
 namespace ash {
+class ColorModeObserver;
 
 // The color provider for system UI. It provides colors for Shield layer, Base
 // layer, Controls layer and Content layer. Shield layer is a combination of
@@ -26,11 +33,12 @@ namespace ash {
 // state of an interactive element (active/inactive states). Content layer means
 // the UI elements, e.g., separator, text, icon. The color of an element in
 // system UI will be the combination of the colors of the four layers.
-class ASH_EXPORT AshColorProvider {
+class ASH_EXPORT AshColorProvider : public SessionObserver {
  public:
-  // The color mode of system UI. Switch "--ash-color-mode" can only set
-  // |color_mode_| to |kLight| or |kDark|, |color_mode_| will be |kDefault| if
-  // the flag is not set.
+  // TODO(minch): Remove AshColorMode, |color_mode_| and DeprecatedGet*
+  // functions once all the deprecated colors have been removed.
+  // The color mode of system UI, which can be set through the dark mode feature
+  // pod in the system tray menu.
   enum class AshColorMode {
     // This is the color mode of current system UI, which is a combination of
     // dark and light mode. e.g, shelf and system tray are dark while many other
@@ -142,10 +150,10 @@ class ASH_EXPORT AshColorProvider {
     const float highlight_opacity;
   };
 
-  AshColorProvider() = default;
+  AshColorProvider();
   AshColorProvider(const AshColorProvider& other) = delete;
   AshColorProvider operator=(const AshColorProvider& other) = delete;
-  ~AshColorProvider() = default;
+  ~AshColorProvider() override;
 
   static AshColorProvider* Get();
 
@@ -157,6 +165,11 @@ class ASH_EXPORT AshColorProvider {
   // power status icon inside status area is a dual tone icon.
   static SkColor GetSecondToneColor(SkColor color_of_first_tone);
 
+  static void RegisterProfilePrefs(PrefRegistrySimple* registry);
+
+  // SessionObserver:
+  void OnActiveUserPrefServiceChanged(PrefService* prefs) override;
+
   // Gets color of Shield layer. See details at the corresponding function of
   // Base layer.
   SkColor DeprecatedGetShieldLayerColor(ShieldLayerType type,
@@ -213,7 +226,16 @@ class ASH_EXPORT AshColorProvider {
                            int button_size,
                            const gfx::VectorIcon& icon);
 
-  AshColorMode color_mode() const { return color_mode_; }
+  void AddObserver(ColorModeObserver* observer);
+  void RemoveObserver(ColorModeObserver* observer);
+
+  // True if pref |kDarkModeEnabled| is true, which means the current color mode
+  // is dark.
+  bool IsDarkModeEnabled() const;
+
+  // Toggles pref |kDarkModeEnabled|.
+  void Toggle();
+
   bool is_themed() const { return is_themed_; }
 
  private:
@@ -250,12 +272,19 @@ class ASH_EXPORT AshColorProvider {
   // muted wallpaper prominent color + SK_ColorWHITE 75%.
   SkColor GetBackgroundThemedColor(AshColorMode color_mode) const;
 
+  // Notifies all the observers on |kDarkModeEnabled|'s change.
+  void NotifyDarkModeEnabledPrefChange();
+
   // Current color mode of system UI.
   AshColorMode color_mode_ = AshColorMode::kDefault;
 
   // Whether the system color mode is themed, by default is true. If true, the
   // background color will be calculated based on extracted wallpaper color.
   bool is_themed_ = true;
+
+  base::ObserverList<ColorModeObserver> observers_;
+  std::unique_ptr<PrefChangeRegistrar> pref_change_registrar_;
+  PrefService* active_user_pref_service_ = nullptr;  // Not owned.
 };
 
 }  // namespace ash

ash/system/dark_mode/color_mode_observer.h

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef ASH_SYSTEM_DARK_MODE_COLOR_MODE_OBSERVER_H_
+#define ASH_SYSTEM_DARK_MODE_COLOR_MODE_OBSERVER_H_
+
+#include "ash/ash_export.h"
+#include "base/observer_list_types.h"
+
+namespace ash {
+
+class ASH_EXPORT ColorModeObserver : public base::CheckedObserver {
+ public:
+  // Called when the color mode changes.
+  virtual void OnColorModeChanged(bool dark_mode_enabled) = 0;
+
+ protected:
+  ~ColorModeObserver() override = default;
+};
+
+}  // namespace ash
+
+#endif  // ASH_SYSTEM_DARK_MODE_COLOR_MODE_OBSERVER_H_

ash/system/dark_mode/dark_mode_detailed_view.cc

@@ -56,8 +56,7 @@ void DarkModeDetailedView::CreateItems() {
 
   toggle_ =
       TrayPopupUtils::CreateToggleButton(this, IDS_ASH_STATUS_TRAY_BLUETOOTH);
-  toggle_->SetIsOn(AshColorProvider::Get()->color_mode() ==
-                   AshColorProvider::AshColorMode::kDark);
+  toggle_->SetIsOn(AshColorProvider::Get()->IsDarkModeEnabled());
   tri_view()->AddView(TriView::Container::END, toggle_);
 
   // Add color mode options.

ash/system/dark_mode/dark_mode_feature_pod_controller.cc

@@ -5,6 +5,8 @@
 #include "ash/system/dark_mode/dark_mode_feature_pod_controller.h"
 
 #include "ash/resources/vector_icons/vector_icons.h"
+#include "ash/session/session_controller_impl.h"
+#include "ash/shell.h"
 #include "ash/strings/grit/ash_strings.h"
 #include "ash/style/ash_color_provider.h"
 #include "ash/system/unified/feature_pod_button.h"
@@ -17,9 +19,12 @@ DarkModeFeaturePodController::DarkModeFeaturePodController(
     UnifiedSystemTrayController* tray_controller)
     : tray_controller_(tray_controller) {
   DCHECK(tray_controller_);
+  AshColorProvider::Get()->AddObserver(this);
 }
 
-DarkModeFeaturePodController::~DarkModeFeaturePodController() = default;
+DarkModeFeaturePodController::~DarkModeFeaturePodController() {
+  AshColorProvider::Get()->RemoveObserver(this);
+}
 
 FeaturePodButton* DarkModeFeaturePodController::CreateButton() {
   DCHECK(!button_);
@@ -29,14 +34,17 @@ FeaturePodButton* DarkModeFeaturePodController::CreateButton() {
       l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_DARK_MODE_BUTTON_LABEL));
   button_->SetLabelTooltip(l10n_util::GetStringUTF16(
       IDS_ASH_STATUS_TRAY_DARK_MODE_SETTINGS_TOOLTIP));
+  // TODO(minch): Add the logic for login screen.
+  button_->SetVisible(
+      Shell::Get()->session_controller()->IsActiveUserSessionStarted());
 
-  UpdateButton();
+  UpdateButton(AshColorProvider::Get()->IsDarkModeEnabled());
   return button_;
 }
 
 void DarkModeFeaturePodController::OnIconPressed() {
   // TODO: Switch dark mode here.
-  UpdateButton();
+  AshColorProvider::Get()->Toggle();
 
   // TODO(amehfooz): Add metrics recording here.
 }
@@ -50,16 +58,18 @@ SystemTrayItemUmaType DarkModeFeaturePodController::GetUmaType() const {
   return SystemTrayItemUmaType::UMA_DARK_MODE;
 }
 
-void DarkModeFeaturePodController::UpdateButton() {
-  const bool is_enabled = AshColorProvider::Get()->color_mode() ==
-                          AshColorProvider::AshColorMode::kDark;
-  button_->SetToggled(is_enabled);
+void DarkModeFeaturePodController::OnColorModeChanged(bool dark_mode_enabled) {
+  UpdateButton(dark_mode_enabled);
+}
+
+void DarkModeFeaturePodController::UpdateButton(bool dark_mode_enabled) {
+  button_->SetToggled(dark_mode_enabled);
   button_->SetSubLabel(l10n_util::GetStringUTF16(
-      is_enabled ? IDS_ASH_STATUS_TRAY_DARK_MODE_ON_STATE
+      dark_mode_enabled ? IDS_ASH_STATUS_TRAY_DARK_MODE_ON_STATE
                         : IDS_ASH_STATUS_TRAY_DARK_MODE_OFF_STATE));
 
   base::string16 tooltip_state = l10n_util::GetStringUTF16(
-      is_enabled ? IDS_ASH_STATUS_TRAY_DARK_MODE_ENABLED_STATE_TOOLTIP
+      dark_mode_enabled ? IDS_ASH_STATUS_TRAY_DARK_MODE_ENABLED_STATE_TOOLTIP
                         : IDS_ASH_STATUS_TRAY_DARK_MODE_DISABLED_STATE_TOOLTIP);
   button_->SetIconTooltip(l10n_util::GetStringFUTF16(
       IDS_ASH_STATUS_TRAY_DARK_MODE_TOGGLE_TOOLTIP, tooltip_state));

ash/system/dark_mode/dark_mode_feature_pod_controller.h

@@ -5,6 +5,7 @@
 #ifndef ASH_SYSTEM_DARK_MODE_DARK_MODE_FEATURE_POD_CONTROLLER_H_
 #define ASH_SYSTEM_DARK_MODE_DARK_MODE_FEATURE_POD_CONTROLLER_H_
 
+#include "ash/system/dark_mode/color_mode_observer.h"
 #include "ash/system/unified/feature_pod_controller_base.h"
 #include "base/macros.h"
 
@@ -13,7 +14,8 @@ namespace ash {
 class UnifiedSystemTrayController;
 
 // Controller of a feature pod button that toggles dark mode for ash.
-class DarkModeFeaturePodController : public FeaturePodControllerBase {
+class DarkModeFeaturePodController : public FeaturePodControllerBase,
+                                     public ColorModeObserver {
  public:
   explicit DarkModeFeaturePodController(
       UnifiedSystemTrayController* tray_controller);
@@ -29,8 +31,11 @@ class DarkModeFeaturePodController : public FeaturePodControllerBase {
   void OnLabelPressed() override;
   SystemTrayItemUmaType GetUmaType() const override;
 
+  // ColorModeObserver:
+  void OnColorModeChanged(bool dark_mode_enabled) override;
+
  private:
-  void UpdateButton();
+  void UpdateButton(bool dark_mode_enabled);
 
   UnifiedSystemTrayController* const tray_controller_;
 

ash/wm/desks/desk_mini_view.cc

@@ -139,10 +139,9 @@ void DeskMiniView::UpdateBorderColor() {
     desk_preview_->SetBorderColor(kInactiveColor);
   } else {
     // Default theme for desks is dark mode.
-    desk_preview_->SetBorderColor(color_provider->color_mode() ==
-                                          AshColorProvider::AshColorMode::kLight
-                                      ? kLightModeActiveColor
-                                      : kDarkModeActiveColor);
+    desk_preview_->SetBorderColor(color_provider->IsDarkModeEnabled()
+                                      ? kDarkModeActiveColor
+                                      : kLightModeActiveColor);
   }
 }