commit 4943182fdfe7adbcc49b10538d7d52b17dd538ff
Author: Tom Anderson <thomasanderson@chromium.org>
Date:   Fri Jul 21 22:35:40 2023 +0000

    [Linux Ui] Set toolkit dark preference based on FDO dark preference
    
    The toolkit color scheme preference is not affected by the
    `org.freedesktop.appearance color-scheme` setting.  It's up to
    apps to manually toggle the toolkit theme based on this setting.
    This is done by libadwaita, libhandy, firefox, and libreoffice.
    
    R=sky
    
    Change-Id: If05e61e6d0ec98ee1a74d442ce29b2ceb5337e86
    Bug: 998903
    Low-Coverage-Reason: No existing tests for dark_mode_manager_linux
    Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4701710
    Reviewed-by: Scott Violet <sky@chromium.org>
    Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
    Cr-Commit-Position: refs/heads/main@{#1173744}

diff --git a/chrome/browser/ui/views/dark_mode_manager_linux.cc b/chrome/browser/ui/views/dark_mode_manager_linux.cc
index 4127327433593..6f054ab76b305 100644
--- a/chrome/browser/ui/views/dark_mode_manager_linux.cc
+++ b/chrome/browser/ui/views/dark_mode_manager_linux.cc
@@ -67,7 +67,7 @@ DarkModeManagerLinux::DarkModeManagerLinux()
   if (auto* linux_ui_theme = ui::GetDefaultLinuxUiTheme()) {
     auto* native_theme = linux_ui_theme->GetNativeTheme();
     native_theme_observer_.Observe(native_theme);
-    SetColorScheme(native_theme->ShouldUseDarkColors());
+    SetColorScheme(native_theme->ShouldUseDarkColors(), true);
   }
 }
 
@@ -80,7 +80,7 @@ DarkModeManagerLinux::~DarkModeManagerLinux() {
 
 void DarkModeManagerLinux::OnNativeThemeUpdated(
     ui::NativeTheme* observed_theme) {
-  SetColorScheme(observed_theme->ShouldUseDarkColors());
+  SetColorScheme(observed_theme->ShouldUseDarkColors(), true);
 }
 
 void DarkModeManagerLinux::OnSignalConnected(const std::string& interface_name,
@@ -114,7 +114,7 @@ void DarkModeManagerLinux::OnPortalSettingChanged(dbus::Signal* signal) {
     return;
   }
 
-  SetColorScheme(new_color_scheme == kFreedesktopColorSchemeDark);
+  SetColorScheme(new_color_scheme == kFreedesktopColorSchemeDark, false);
 }
 
 void DarkModeManagerLinux::OnReadColorSchemeResponse(dbus::Response* response) {
@@ -137,13 +137,23 @@ void DarkModeManagerLinux::OnReadColorSchemeResponse(dbus::Response* response) {
     return;
   }
 
-  // Ignore future updates from the toolkit theme.
-  native_theme_observer_.Reset();
+  // Once we read the org.freedesktop.appearance color-scheme setting successfully,
+  // it should always take precedence over the toolkit color scheme.
+  ignore_toolkit_theme_changes_ = true;
 
-  SetColorScheme(new_color_scheme == kFreedesktopColorSchemeDark);
+  SetColorScheme(new_color_scheme == kFreedesktopColorSchemeDark, false);
 }
 
-void DarkModeManagerLinux::SetColorScheme(bool prefer_dark_theme) {
+void DarkModeManagerLinux::SetColorScheme(bool prefer_dark_theme,
+                                          bool from_toolkit_theme) {
+  if (from_toolkit_theme && ignore_toolkit_theme_changes_) {
+    return;
+  }
+  if (!from_toolkit_theme) {
+    for (auto* linux_ui_theme : ui::GetLinuxUiThemes()) {
+      linux_ui_theme->SetDarkTheme(prefer_dark_theme);
+    }
+  }
   if (prefer_dark_theme_ == prefer_dark_theme) {
     return;
   }
diff --git a/chrome/browser/ui/views/dark_mode_manager_linux.h b/chrome/browser/ui/views/dark_mode_manager_linux.h
index 34b07ffadbbef..e00d8617e0e23 100644
--- a/chrome/browser/ui/views/dark_mode_manager_linux.h
+++ b/chrome/browser/ui/views/dark_mode_manager_linux.h
@@ -44,12 +44,13 @@ class DarkModeManagerLinux : public NativeThemeObserver {
   void OnReadColorSchemeResponse(dbus::Response* response);
 
   // Sets `prefer_dark_theme_` and propagates to the web theme.
-  void SetColorScheme(bool prefer_dark_theme);
+  void SetColorScheme(bool prefer_dark_theme, bool from_toolkit_theme);
 
   scoped_refptr<dbus::Bus> bus_;
   raw_ptr<dbus::ObjectProxy> settings_proxy_;
 
   bool prefer_dark_theme_ = false;
+  bool ignore_toolkit_theme_changes_ = false;
 
   base::ScopedObservation<NativeTheme, NativeThemeObserver>
       native_theme_observer_{this};
diff --git a/ui/gtk/gtk_ui.cc b/ui/gtk/gtk_ui.cc
index 2b6bb89e3071e..a463500570c03 100644
--- a/ui/gtk/gtk_ui.cc
+++ b/ui/gtk/gtk_ui.cc
@@ -463,6 +463,14 @@ bool GtkUi::PreferDarkTheme() const {
   return dark;
 }
 
+void GtkUi::SetDarkTheme(bool dark) {
+  auto* settings = gtk_settings_get_default();
+  g_object_set(settings, "gtk-application-prefer-dark-theme", dark, nullptr);
+  // OnThemeChanged() will be called via the
+  // notify::gtk-application-prefer-dark-theme handler to update the native
+  // theme.
+}
+
 bool GtkUi::AnimationsEnabled() const {
   gboolean animations_enabled = false;
   g_object_get(gtk_settings_get_default(), "gtk-enable-animations",
diff --git a/ui/gtk/gtk_ui.h b/ui/gtk/gtk_ui.h
index 573ea4066881b..53c02c50dac53 100644
--- a/ui/gtk/gtk_ui.h
+++ b/ui/gtk/gtk_ui.h
@@ -106,6 +106,7 @@ class GtkUi : public ui::LinuxUiAndTheme {
   void GetInactiveSelectionBgColor(SkColor* color) const override;
   void GetInactiveSelectionFgColor(SkColor* color) const override;
   bool PreferDarkTheme() const override;
+  void SetDarkTheme(bool dark) override;
   std::unique_ptr<ui::NavButtonProvider> CreateNavButtonProvider() override;
   ui::WindowFrameProvider* GetWindowFrameProvider(bool solid_frame) override;
 
diff --git a/ui/linux/fake_linux_ui.cc b/ui/linux/fake_linux_ui.cc
index d236a0919f66b..8b67f04c25e7d 100644
--- a/ui/linux/fake_linux_ui.cc
+++ b/ui/linux/fake_linux_ui.cc
@@ -93,6 +93,8 @@ bool FakeLinuxUi::PreferDarkTheme() const {
   return false;
 }
 
+void FakeLinuxUi::SetDarkTheme(bool dark) {}
+
 bool FakeLinuxUi::AnimationsEnabled() const {
   return true;
 }
diff --git a/ui/linux/fake_linux_ui.h b/ui/linux/fake_linux_ui.h
index 87aa82c930a35..daba20d196a7c 100644
--- a/ui/linux/fake_linux_ui.h
+++ b/ui/linux/fake_linux_ui.h
@@ -64,6 +64,7 @@ class FakeLinuxUi : public LinuxUiAndTheme {
   void GetInactiveSelectionBgColor(SkColor* color) const override;
   void GetInactiveSelectionFgColor(SkColor* color) const override;
   bool PreferDarkTheme() const override;
+  void SetDarkTheme(bool dark) override;
   std::unique_ptr<ui::NavButtonProvider> CreateNavButtonProvider() override;
   ui::WindowFrameProvider* GetWindowFrameProvider(bool solid_frame) override;
 };
diff --git a/ui/linux/fallback_linux_ui.cc b/ui/linux/fallback_linux_ui.cc
index ab116fda42b22..6d77be047e202 100644
--- a/ui/linux/fallback_linux_ui.cc
+++ b/ui/linux/fallback_linux_ui.cc
@@ -112,7 +112,11 @@ LinuxUi::WindowFrameAction FallbackLinuxUi::GetWindowFrameAction(
 }
 
 bool FallbackLinuxUi::PreferDarkTheme() const {
-  return false;
+  return theme_is_dark_;
+}
+
+void FallbackLinuxUi::SetDarkTheme(bool dark) {
+  theme_is_dark_ = dark;
 }
 
 bool FallbackLinuxUi::AnimationsEnabled() const {
diff --git a/ui/linux/fallback_linux_ui.h b/ui/linux/fallback_linux_ui.h
index 0d0df25ec2caf..9901d4939400d 100644
--- a/ui/linux/fallback_linux_ui.h
+++ b/ui/linux/fallback_linux_ui.h
@@ -65,12 +65,14 @@ class FallbackLinuxUi : public LinuxUiAndTheme {
   void GetInactiveSelectionBgColor(SkColor* color) const override;
   void GetInactiveSelectionFgColor(SkColor* color) const override;
   bool PreferDarkTheme() const override;
+  void SetDarkTheme(bool dark) override;
   std::unique_ptr<ui::NavButtonProvider> CreateNavButtonProvider() override;
   ui::WindowFrameProvider* GetWindowFrameProvider(bool solid_frame) override;
 
  private:
   std::string default_font_family_;
   gfx::FontRenderParams default_font_render_params_;
+  bool theme_is_dark_ = false;
 };
 
 }  // namespace ui
diff --git a/ui/linux/linux_ui.h b/ui/linux/linux_ui.h
index 45b36fbeeabc4..a47134d7fa672 100644
--- a/ui/linux/linux_ui.h
+++ b/ui/linux/linux_ui.h
@@ -300,6 +300,10 @@ class COMPONENT_EXPORT(LINUX_UI) LinuxUiTheme {
   // preferred.
   virtual bool PreferDarkTheme() const = 0;
 
+  // Override the toolkit's dark mode preference.  Used when the dark mode
+  // setting is provided by org.freedesktop.appearance instead of the toolkit.
+  virtual void SetDarkTheme(bool dark) = 0;
+
   // Returns a new NavButtonProvider, or nullptr if the underlying
   // toolkit does not support drawing client-side navigation buttons.
   virtual std::unique_ptr<NavButtonProvider> CreateNavButtonProvider() = 0;
diff --git a/ui/linux/linux_ui_factory.cc b/ui/linux/linux_ui_factory.cc
index 5555ff3bf21f4..21be358d2af8e 100644
--- a/ui/linux/linux_ui_factory.cc
+++ b/ui/linux/linux_ui_factory.cc
@@ -10,6 +10,7 @@
 #include "base/command_line.h"
 #include "base/environment.h"
 #include "base/nix/xdg_util.h"
+#include "base/no_destructor.h"
 #include "base/strings/string_util.h"
 #include "build/chromecast_buildflags.h"
 #include "ui/base/buildflags.h"
@@ -35,10 +36,16 @@ namespace {
 
 const char kUiToolkitFlag[] = "ui-toolkit";
 
+std::vector<LinuxUiTheme*>& GetLinuxUiThemesImpl() {
+  static base::NoDestructor<std::vector<LinuxUiTheme*>> themes;
+  return *themes;
+}
+
 std::unique_ptr<LinuxUiAndTheme> CreateGtkUi() {
 #if BUILDFLAG(USE_GTK)
   auto gtk_ui = BuildGtkUi();
   if (gtk_ui->Initialize()) {
+    GetLinuxUiThemesImpl().push_back(gtk_ui.get());
     return gtk_ui;
   }
 #endif
@@ -61,6 +68,7 @@ std::unique_ptr<LinuxUiAndTheme> CreateQtUi() {
 #if BUILDFLAG(USE_QT)
   auto qt_ui = qt::CreateQtUi(GetGtkUi());
   if (qt_ui->Initialize()) {
+    GetLinuxUiThemesImpl().push_back(qt_ui.get());
     return qt_ui;
   }
 #endif
@@ -156,6 +164,10 @@ LinuxUiTheme* GetLinuxUiTheme(SystemTheme system_theme) {
   }
 }
 
+const std::vector<LinuxUiTheme*>& GetLinuxUiThemes() {
+  return GetLinuxUiThemesImpl();
+}
+
 SystemTheme GetDefaultSystemTheme() {
   std::unique_ptr<base::Environment> env = base::Environment::Create();
 
diff --git a/ui/linux/linux_ui_factory.h b/ui/linux/linux_ui_factory.h
index 5d4f4f4761972..2f4820f2c6240 100644
--- a/ui/linux/linux_ui_factory.h
+++ b/ui/linux/linux_ui_factory.h
@@ -32,6 +32,10 @@ LinuxUiTheme* GetDefaultLinuxUiTheme();
 COMPONENT_EXPORT(LINUX_UI_FACTORY)
 LinuxUiTheme* GetLinuxUiTheme(SystemTheme system_theme);
 
+// Returns all `LinuxUiTheme`s that have been created.
+COMPONENT_EXPORT(LINUX_UI_FACTORY)
+const std::vector<LinuxUiTheme*>& GetLinuxUiThemes();
+
 COMPONENT_EXPORT(LINUX_UI_FACTORY)
 SystemTheme GetDefaultSystemTheme();
 
diff --git a/ui/qt/qt_ui.cc b/ui/qt/qt_ui.cc
index cd12c72a3cad4..37e165d76305e 100644
--- a/ui/qt/qt_ui.cc
+++ b/ui/qt/qt_ui.cc
@@ -355,6 +355,11 @@ bool QtUi::PreferDarkTheme() const {
       shim_->GetColor(ColorType::kWindowBg, ColorState::kNormal));
 }
 
+DISABLE_CFI_VCALL
+void QtUi::SetDarkTheme(bool dark) {
+  // Qt::ColorScheme is only available in QT 6.5 and later.
+}
+
 DISABLE_CFI_VCALL
 bool QtUi::AnimationsEnabled() const {
   return shim_->GetAnimationDurationMs() > 0;
diff --git a/ui/qt/qt_ui.h b/ui/qt/qt_ui.h
index 38ce8719ee1d8..787a9556b1264 100644
--- a/ui/qt/qt_ui.h
+++ b/ui/qt/qt_ui.h
@@ -82,6 +82,7 @@ class QtUi : public ui::LinuxUiAndTheme, QtInterface::Delegate {
   void GetInactiveSelectionBgColor(SkColor* color) const override;
   void GetInactiveSelectionFgColor(SkColor* color) const override;
   bool PreferDarkTheme() const override;
+  void SetDarkTheme(bool dark) override;
   std::unique_ptr<ui::NavButtonProvider> CreateNavButtonProvider() override;
   ui::WindowFrameProvider* GetWindowFrameProvider(bool solid_frame) override;