Remove more remnants of dark mode from old NTP-ish UIs

BUG=965811

Change-Id: I70024269a3239b1920d0cd73f79ab9242fde6ac6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1671467
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Auto-Submit: Dan Beam <dbeam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#671476}

chrome/browser/ui/webui/ntp/new_tab_ui.cc

@@ -53,11 +53,7 @@ const char* GetHtmlTextDirection(const base::string16& text) {
 ///////////////////////////////////////////////////////////////////////////////
 // NewTabUI
 
-NewTabUI::NewTabUI(content::WebUI* web_ui)
-    : content::WebUIController(web_ui),
-      dark_mode_observer_(ui::NativeTheme::GetInstanceForNativeUi(),
-                          base::BindRepeating(&NewTabUI::OnDarkModeChanged,
-                                              base::Unretained(this))) {
+NewTabUI::NewTabUI(content::WebUI* web_ui) : content::WebUIController(web_ui) {
   web_ui->OverrideTitle(l10n_util::GetStringUTF16(IDS_NEW_TAB_TITLE));
 
   Profile* profile = GetProfile();
@@ -76,8 +72,6 @@ NewTabUI::NewTabUI(content::WebUI* web_ui)
   pref_change_registrar_.Add(
       prefs::kWebKitDefaultFontSize,
       base::Bind(&NewTabUI::OnDefaultFontSizeChanged, base::Unretained(this)));
-
-  dark_mode_observer_.Start();
 }
 
 NewTabUI::~NewTabUI() {}
@@ -91,16 +85,6 @@ void NewTabUI::OnShowBookmarkBarChanged() {
                                          attached);
 }
 
-void NewTabUI::OnDarkModeChanged(bool /*dark_mode*/) {
-  if (!web_ui() || !web_ui()->CanCallJavascript())
-    return;
-
-  bool enabled = base::FeatureList::IsEnabled(features::kWebUIDarkMode);
-  web_ui()->CallJavascriptFunctionUnsafe(
-      "document.documentElement.toggleAttribute", base::Value("dark"),
-      base::Value(enabled && dark_mode_observer_.InDarkMode()));
-}
-
 void NewTabUI::OnDefaultFontSizeChanged() {
   web_ui()->CallJavascriptFunctionUnsafe("ntp.defaultFontSizeChanged");
 }

chrome/browser/ui/webui/ntp/new_tab_ui.h

@@ -10,7 +10,6 @@
 #include "components/prefs/pref_change_registrar.h"
 #include "content/public/browser/url_data_source.h"
 #include "content/public/browser/web_ui_controller.h"
-#include "ui/native_theme/dark_mode_observer.h"
 
 class GURL;
 class Profile;
@@ -74,14 +73,11 @@ class NewTabUI : public content::WebUIController {
     DISALLOW_COPY_AND_ASSIGN(NewTabHTMLSource);
   };
 
-  void OnDarkModeChanged(bool dark_mode);
   void OnDefaultFontSizeChanged();
   void OnShowBookmarkBarChanged();
 
   Profile* GetProfile() const;
 
-  ui::DarkModeObserver dark_mode_observer_;
-
   PrefChangeRegistrar pref_change_registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(NewTabUI);

chrome/browser/ui/webui/ntp/ntp_resource_cache.cc

@@ -347,8 +347,6 @@ void NTPResourceCache::CreateNewTabGuestHTML() {
       l10n_util::GetStringUTF16(guest_tab_link_ids));
   localized_strings.SetString("learnMoreLink", guest_tab_link);
 
-  SetDarkKey(&localized_strings);
-
   const std::string& app_locale = g_browser_process->GetApplicationLocale();
   webui::SetLoadTimeDataDefaults(app_locale, &localized_strings);
 
@@ -467,8 +465,6 @@ void NTPResourceCache::CreateNewTabHTML() {
       "isUserSignedIn",
       IdentityManagerFactory::GetForProfile(profile_)->HasPrimaryAccount());
 
-  SetDarkKey(&load_time_data);
-
   // Load the new tab page appropriate for this build.
   base::StringPiece new_tab_html(
       ui::ResourceBundle::GetSharedInstance().GetRawDataResource(
@@ -584,11 +580,3 @@ void NTPResourceCache::CreateNewTabCSS() {
       ui::ReplaceTemplateExpressions(new_tab_theme_css, substitutions);
   new_tab_css_ = base::RefCountedString::TakeString(&css_string);
 }
-
-void NTPResourceCache::SetDarkKey(base::Value* dict) {
-  DCHECK(dict && dict->is_dict());
-  bool use_dark =
-      base::FeatureList::IsEnabled(features::kWebUIDarkMode) &&
-      ui::NativeTheme::GetInstanceForNativeUi()->SystemDarkModeEnabled();
-  dict->SetKey("dark", base::Value(use_dark ? "dark" : ""));
-}