Disable "Reset to Default theme"/"Use classic theme" correctly.

chrome/browser/ui/gtk/options/content_page_gtk.cc

 // Copyright (c) 2011 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.
 
 #include "chrome/browser/ui/gtk/options/content_page_gtk.h"
 
 #include <string>
 
 #include "base/command_line.h"
 #include "base/utf_string_conversions.h"
@@ skipping 183 matching lines @@
 #if defined(TOOLKIT_GTK)
   GtkThemeProvider* provider = GtkThemeProvider::GetFrom(profile());
   bool is_gtk_theme = provider->UseGtkTheme();
   gtk_widget_set_sensitive(gtk_theme_button_, !is_gtk_theme);
 #else
   BrowserThemeProvider* provider =
       reinterpret_cast<BrowserThemeProvider*>(profile()->GetThemeProvider());
   bool is_gtk_theme = false;
 #endif
 
-  bool is_classic_theme = !is_gtk_theme && provider->GetThemeID().empty();
+  bool is_classic_theme = !is_gtk_theme && provider->UsingDefaultTheme();
   gtk_widget_set_sensitive(themes_reset_button_, !is_classic_theme);
 }
 
 GtkWidget* ContentPageGtk::InitPasswordSavingGroup() {
   GtkWidget* vbox = gtk_vbox_new(FALSE, gtk_util::kControlSpacing);
 
   // Ask to save radio button.
   passwords_asktosave_radio_ = gtk_radio_button_new_with_label(NULL,
       l10n_util::GetStringUTF8(IDS_OPTIONS_PASSWORDS_ASKTOSAVE).c_str());
   g_signal_connect(passwords_asktosave_radio_, "toggled",
@@ skipping 362 matching lines @@
   if (response == GTK_RESPONSE_ACCEPT) {
     sync_service_->DisableForUser();
     ProfileSyncService::SyncEvent(ProfileSyncService::STOP_FROM_OPTIONS);
   }
   gtk_widget_destroy(widget);
 }
 
 void ContentPageGtk::OnPrivacyDashboardLinkClicked(GtkWidget* widget) {
   BrowserList::GetLastActive()->OpenPrivacyDashboardTabAndActivate();
 }