Files.app: Start to use PiexLoader in image loader.

ui/file_manager/image_loader/compiled_resources.gyp

 # 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.
 {
   'targets': [
     {
       'target_name': 'background',
       'variables': {
         'depends': [
+          "../file_manager/common/js/file_type.js",
           "../file_manager/foreground/js/metadata/image_orientation.js",
           'cache.js',
           'image_loader.js',
           'piex_loader.js',
           'request.js',
           'scheduler.js',
         ],
         'externs': [
           '<(CLOSURE_DIR)/externs/chrome_send_externs.js',
           '<(CLOSURE_DIR)/externs/chrome_extensions.js',
           '<(CLOSURE_DIR)/externs/file_manager_private.js',
         ],
       },
       'includes': [
         '../../../third_party/closure_compiler/compile_js.gypi'
       ],
     }
   ],
 }