linux and chromeos: Turn on -Wunused-const-variable.

chrome/browser/icon_loader_chromeos.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/icon_loader.h"
 
 #include <map>
 #include <string>
 #include <utility>
 
@@ skipping 50 matching lines @@
 const IdrBySize kGenericIdrs = {
   IDR_FILE_MANAGER_IMG_FILETYPE_GENERIC,
   IDR_FILE_MANAGER_IMG_FILETYPE_LARGE_GENERIC,
   IDR_FILE_MANAGER_IMG_FILETYPE_LARGE_GENERIC
 };
 const IdrBySize kImageIdrs = {
   IDR_FILE_MANAGER_IMG_FILETYPE_IMAGE,
   IDR_FILE_MANAGER_IMG_FILETYPE_IMAGE,
   IDR_FILE_MANAGER_IMG_FILETYPE_IMAGE
 };
+#if defined(USE_PROPRIETARY_CODECS)
 const IdrBySize kPdfIdrs = {
   IDR_FILE_MANAGER_IMG_FILETYPE_PDF,
   IDR_FILE_MANAGER_IMG_FILETYPE_PDF,
   IDR_FILE_MANAGER_IMG_FILETYPE_PDF
 };
+#endif
 const IdrBySize kVideoIdrs = {
   IDR_FILE_MANAGER_IMG_FILETYPE_VIDEO,
   IDR_FILE_MANAGER_IMG_FILETYPE_LARGE_VIDEO,
   IDR_FILE_MANAGER_IMG_FILETYPE_LARGE_VIDEO
 };
 
 IconMapper::IconMapper() {
   // The code below should match translation in
   // chrome/browser/resources/file_manager/js/file_manager.js
   // chrome/browser/resources/file_manager/css/file_manager.css
@@ skipping 107 matching lines @@
       LAZY_INSTANCE_INITIALIZER;
   int idr = icon_mapper.Get().Lookup(group_, icon_size_);
   ResourceBundle& rb = ResourceBundle::GetSharedInstance();
   gfx::ImageSkia image_skia(ResizeImage(*(rb.GetImageNamed(idr)).ToImageSkia(),
                                         IconSizeToDIPSize(icon_size_)));
   image_skia.MakeThreadSafe();
   image_.reset(new gfx::Image(image_skia));
   target_message_loop_->PostTask(
       FROM_HERE, base::Bind(&IconLoader::NotifyDelegate, this));
 }