Introduce ItemPosition class for enhanced bookmarks.

components/enhanced_bookmarks.gypi

 # 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': 'enhanced_bookmarks',
       'type': 'static_library',
       'include_dirs': [
@@ skipping 12 matching lines @@
       'sources': [
         'enhanced_bookmarks/bookmark_image_service.cc',
         'enhanced_bookmarks/bookmark_image_service.h',
         'enhanced_bookmarks/enhanced_bookmark_utils.cc',
         'enhanced_bookmarks/enhanced_bookmark_utils.h',
         'enhanced_bookmarks/image_store.cc',
         'enhanced_bookmarks/image_store.h',
         'enhanced_bookmarks/image_store_util.cc',
         'enhanced_bookmarks/image_store_util.h',
         'enhanced_bookmarks/image_store_util_ios.mm',
+        'enhanced_bookmarks/item_position.cc',
+        'enhanced_bookmarks/item_position.h',
         'enhanced_bookmarks/metadata_accessor.cc',
         'enhanced_bookmarks/metadata_accessor.h',
         'enhanced_bookmarks/persistent_image_store.cc',
         'enhanced_bookmarks/persistent_image_store.h',
       ],
       'conditions': [
         ['OS=="android"', {
           'sources': [
             'enhanced_bookmarks/android/component_jni_registrar.cc',
             'enhanced_bookmarks/android/component_jni_registrar.h',
@@ skipping 61 matching lines @@
           ],
           'variables': {
             'jni_gen_package': 'enhanced_bookmarks',
           },
           'includes': [ '../build/jni_generator.gypi' ],
         },
       ],
     }]
   ],
 }