Views: factor out Combobox background and const-ify style

ui/gfx/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 
 if (is_android) {
   import("//build/config/android/config.gni")
   import("//build/config/android/rules.gni")
@@ skipping 130 matching lines @@
     "platform_font.h",
     "platform_font_android.cc",
     "platform_font_ios.h",
     "platform_font_ios.mm",
     "platform_font_linux.cc",
     "platform_font_linux.h",
     "platform_font_mac.h",
     "platform_font_mac.mm",
     "platform_font_win.cc",
     "platform_font_win.h",
+    "scoped_canvas.cc",
     "scoped_canvas.h",
     "scoped_cg_context_save_gstate_mac.h",
     "scoped_ns_graphics_context_save_gstate_mac.h",
     "scoped_ns_graphics_context_save_gstate_mac.mm",
     "scoped_ui_graphics_push_context_ios.h",
     "scoped_ui_graphics_push_context_ios.mm",
     "scrollbar_size.cc",
     "scrollbar_size.h",
     "selection_model.cc",
     "selection_model.h",
@@ skipping 654 matching lines @@
 if (is_android) {
   generate_jni("gfx_jni_headers") {
     sources = [
       "../android/java/src/org/chromium/ui/gfx/BitmapHelper.java",
       "../android/java/src/org/chromium/ui/gfx/DeviceDisplayInfo.java",
       "../android/java/src/org/chromium/ui/gfx/ViewConfigurationHelper.java",
     ]
     jni_package = "gfx"
   }
 }