Settings WebUI: use system theme when theme id is specified and system theme setting is true

Bug: 810636
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: Ie72810052b3b379f2b5d6bc26d5c6e08a00c330b
Reviewed-on: https://chromium-review.googlesource.com/959238Reviewed-by: Peter Kotwicz <pkotwicz@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Commit-Queue: Esmael El-Moslimany <aee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#544097}

chrome/browser/resources/settings/appearance_page/appearance_page.js

@@ -274,7 +274,7 @@ Polymer({
    * @private
    */
   themeChanged_: function(themeId, useSystemTheme) {
-    if (themeId) {
+    if (themeId.length > 0) {
       assert(!useSystemTheme);
 
       this.browserProxy_.getThemeInfo(themeId).then(info => {

chrome/browser/themes/theme_service.cc

@@ -566,7 +566,10 @@ void ThemeService::ClearAllThemeData() {
                             weak_ptr_factory_.GetWeakPtr(), true));
 }
 
+void ThemeService::FixInconsistentPreferencesIfNeeded() {}
+
 void ThemeService::LoadThemePrefs() {
+  FixInconsistentPreferencesIfNeeded();
   PrefService* prefs = profile_->GetPrefs();
 
   std::string current_id = GetThemeID();

chrome/browser/themes/theme_service.h

@@ -171,6 +171,10 @@ class ThemeService : public content::NotificationObserver, public KeyedService {
   virtual bool ShouldUseNativeFrame() const;
   bool HasCustomImage(int id) const;
 
+  // If there is an inconsistency in preferences, change preferences to a
+  // consistent state.
+  virtual void FixInconsistentPreferencesIfNeeded();
+
   Profile* profile() const { return profile_; }
 
   void set_ready() { ready_ = true; }

chrome/browser/themes/theme_service_aurax11.cc

@@ -101,3 +101,14 @@ bool ThemeServiceAuraX11::UsingSystemTheme() const {
   return theme_supplier &&
          theme_supplier->get_theme_type() == CustomThemeSupplier::NATIVE_X11;
 }
+
+void ThemeServiceAuraX11::FixInconsistentPreferencesIfNeeded() {
+  PrefService* prefs = profile()->GetPrefs();
+
+  // When using the system theme, the theme ID should match the default. Give
+  // precedence to the non-default theme specified.
+  if (GetThemeID() != ThemeService::kDefaultThemeID &&
+      prefs->GetBoolean(prefs::kUsesSystemTheme)) {
+    prefs->SetBoolean(prefs::kUsesSystemTheme, false);
+  }
+}

chrome/browser/themes/theme_service_aurax11.h

@@ -21,6 +21,7 @@ class ThemeServiceAuraX11 : public ThemeService {
   bool IsSystemThemeDistinctFromDefaultTheme() const override;
   bool UsingDefaultTheme() const override;
   bool UsingSystemTheme() const override;
+  void FixInconsistentPreferencesIfNeeded() override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(ThemeServiceAuraX11);

chrome/browser/themes/theme_service_unittest.cc

@@ -400,6 +400,26 @@ TEST_F(ThemeServiceSupervisedUserTest, SupervisedUserThemeReplacesNativeTheme) {
   EXPECT_EQ(get_theme_supplier(theme_service)->get_theme_type(),
             CustomThemeSupplier::SUPERVISED_USER_THEME);
 }
+
+TEST_F(ThemeServiceTest, UserThemeTakesPrecedenceOverSystemTheme) {
+  ThemeService* theme_service =
+      ThemeServiceFactory::GetForProfile(profile_.get());
+
+  base::ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+  const std::string& extension_id = LoadUnpackedThemeAt(temp_dir.GetPath());
+  ASSERT_EQ(extension_id, theme_service->GetThemeID());
+
+  // Set preference |prefs::kUsesSystemTheme| to true which conflicts with
+  // having a user theme selected.
+  profile_->GetPrefs()->SetBoolean(prefs::kUsesSystemTheme, true);
+  EXPECT_TRUE(profile_->GetPrefs()->GetBoolean(prefs::kUsesSystemTheme));
+
+  // Initialization should fix the preference inconsistency.
+  theme_service->Init(profile_.get());
+  ASSERT_EQ(extension_id, theme_service->GetThemeID());
+  EXPECT_FALSE(profile_->GetPrefs()->GetBoolean(prefs::kUsesSystemTheme));
+}
 #endif // defined(OS_LINUX) && !defined(OS_CHROMEOS)
 #endif // BUILDFLAG(ENABLE_SUPERVISED_USERS)