Gtk3: Use menubar instead of headerbar on version less than 3.10

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 <X11/Xcursor/Xcursor.h>
 #include <dlfcn.h>
 #include <math.h>
 #include <pango/pango.h>
@@ skipping 846 matching lines @@
   colors_[ThemeProperties::COLOR_NTP_TEXT] = native_theme_->GetSystemColor(
       ui::NativeTheme::kColorId_TextfieldDefaultColor);
   // The NTP header is the color that surrounds the current active
   // thumbnail on the NTP, and acts as the border of the "Recent
   // Links" box. It would be awesome if they were separated so we
   // could use GetBorderColor() for the border around the "Recent
   // Links" section, but matching the frame color is more important.
   colors_[ThemeProperties::COLOR_NTP_HEADER] =
       colors_[ThemeProperties::COLOR_FRAME];
 #else
-  SkColor frame_color = GetBgColor("#headerbar.header-bar.titlebar");
-  SkColor frame_color_inactive =
-      GetBgColor("#headerbar.header-bar.titlebar:backdrop");
+  std::string header_selector = GtkVersionCheck(3, 10)
+                                    ? "#headerbar.header-bar.titlebar"
+                                    : "GtkMenuBar#menubar";
+  SkColor frame_color = GetBgColor(header_selector);
+  SkColor frame_color_inactive = GetBgColor(header_selector + ":backdrop");
   colors_[ThemeProperties::COLOR_FRAME] = frame_color;
   colors_[ThemeProperties::COLOR_FRAME_INACTIVE] = frame_color_inactive;
   colors_[ThemeProperties::COLOR_FRAME_INCOGNITO] =
       color_utils::HSLShift(frame_color, kDefaultTintFrameIncognito);
   colors_[ThemeProperties::COLOR_FRAME_INCOGNITO_INACTIVE] =
       color_utils::HSLShift(frame_color_inactive, kDefaultTintFrameIncognito);
 
   SkColor toolbar_color = GetBgColor("GtkToolbar#toolbar");
   SkColor toolbar_text_color = color_utils::GetReadableColor(
       GetFgColor("GtkToolbar#toolbar GtkLabel#label"),
@@ skipping 34 matching lines @@
   // Separates entries in the downloads bar.
   colors_[ThemeProperties::COLOR_TOOLBAR_VERTICAL_SEPARATOR] =
       toolbar_button_border;
   // Separates the bookmark bar from the web content.
   colors_[ThemeProperties::COLOR_DETACHED_BOOKMARK_BAR_SEPARATOR] =
       toolbar_button_border;
 
   // These colors represent the border drawn around tabs and between
   // the tabstrip and toolbar.
   SkColor toolbar_top_separator = GetToolbarTopSeparatorColor(
-      GetBorderColor("#headerbar.header-bar.titlebar GtkButton#button"),
-      frame_color, toolbar_button_border, toolbar_color);
+      GetBorderColor(header_selector + " GtkButton#button"), frame_color,
+      toolbar_button_border, toolbar_color);
   SkColor toolbar_top_separator_inactive = GetToolbarTopSeparatorColor(
-      GetBorderColor(
-          "#headerbar.header-bar.titlebar:backdrop GtkButton#button"),
+      GetBorderColor(header_selector + ":backdrop GtkButton#button"),
       frame_color_inactive, toolbar_button_border, toolbar_color);
   // Unlike with toolbars, we always want a border around tabs, so let
   // ThemeService choose the border color if the theme doesn't provide one.
   if (SkColorGetA(toolbar_top_separator) &&
       SkColorGetA(toolbar_top_separator_inactive)) {
     colors_[ThemeProperties::COLOR_TOOLBAR_TOP_SEPARATOR] =
         toolbar_top_separator;
     colors_[ThemeProperties::COLOR_TOOLBAR_TOP_SEPARATOR_INACTIVE] =
         toolbar_top_separator_inactive;
   }
@@ skipping 130 matching lines @@
 
 float GtkUi::GetDeviceScaleFactor() const {
   return device_scale_factor_;
 }
 
 }  // namespace libgtkui
 
 views::LinuxUI* BuildGtkUi() {
   return new libgtkui::GtkUi;
 }