Fix bug 139829: Panels [Linux]: Dark titlebar theme only works with Classic...

Fix bug 139829:	Panels [Linux]: Dark titlebar theme only works with Classic theme, not with GTK+ theme

BUG=139829
TEST=Manual test by launching panels and switching themes


Review URL: https://chromiumcodereview.appspot.com/10832141

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149908 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/panels/panel_browser_window_gtk.cc

@@ -143,7 +143,8 @@ bool PanelBrowserWindowGtk::UsingDefaultTheme() const {
     return true;
 
   GtkThemeService* theme_provider = GtkThemeService::GetFrom(panel_->profile());
-  return theme_provider->UsingDefaultTheme();
+  return theme_provider->UsingDefaultTheme() ||
+         theme_provider->UsingNativeTheme();
 }
 
 bool PanelBrowserWindowGtk::GetWindowEdge(int x, int y, GdkWindowEdge* edge) {