Try to improve toolbar separator coloration for themed browser windows.

chrome/browser/ui/libgtkui/gtk_ui.cc

 // Copyright (c) 2012 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/libgtkui/gtk_ui.h"
 
 #include <math.h>
 #include <pango/pango.h>
 #include <X11/Xcursor/Xcursor.h>
 
@@ skipping 868 matching lines @@
 
   colors_[ThemeProperties::COLOR_TAB_THROBBER_SPINNING] =
       native_theme_->GetSystemColor(
           ui::NativeTheme::kColorId_ThrobberSpinningColor);
   colors_[ThemeProperties::COLOR_TAB_THROBBER_WAITING] =
       native_theme_->GetSystemColor(
           ui::NativeTheme::kColorId_ThrobberWaitingColor);
 
 #if GTK_MAJOR_VERSION > 2
   colors_[ThemeProperties::COLOR_TOOLBAR_BOTTOM_SEPARATOR] =
-      colors_[ThemeProperties::COLOR_DETACHED_BOOKMARK_BAR_SEPARATOR] =
-          GetBorderColor("GtkToolbar#toolbar.primary-toolbar");
+      GetBorderColor("GtkToolbar#toolbar.primary-toolbar");
 #endif
 }
 
 void GtkUi::LoadCursorTheme() {
   GtkSettings* settings = gtk_settings_get_default();
 
   gchar* theme = nullptr;
   gint size = 0;
   g_object_get(settings, "gtk-cursor-theme-name", &theme,
                "gtk-cursor-theme-size", &size, nullptr);
@@ skipping 152 matching lines @@
 
 float GtkUi::GetDeviceScaleFactor() const {
   return device_scale_factor_;
 }
 
 }  // namespace libgtkui
 
 views::LinuxUI* BuildGtkUi() {
   return new libgtkui::GtkUi;
 }