[filebrowser] In Gallery, do not allow file names starting with dot.

chrome/browser/resources/file_manager/js/mock_chrome.js

 // 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.
 
 function MockEventSource() {
   this.listeners_ = [];
 }
 
 MockEventSource.prototype.addListener = function(listener) {
   this.listeners_.push(listener);
@@ skipping 239 matching lines @@
       GALLERY_CROP: 'Crop',
       GALLERY_EXPOSURE: 'Brightness',
       GALLERY_BRIGHTNESS: 'Brightness',
       GALLERY_CONTRAST: 'Contrast',
       GALLERY_ROTATE_LEFT: 'Left',
       GALLERY_ROTATE_RIGHT: 'Right',
       GALLERY_ENTER_WHEN_DONE: 'Press Enter when done',
       GALLERY_UNDO: 'Undo',
       GALLERY_REDO: 'Redo',
       GALLERY_FILE_EXISTS: 'File already exists',
+      GALLERY_FILE_HIDDEN_NAME: 'Names starting with dot are reserved ' +
+          'for the system. Please choose another name.',
 
       CONFIRM_OVERWRITE_FILE: 'A file named "$1" already exists. Do you want to replace it?',
       FILE_ALREADY_EXISTS: 'The file named "$1" already exists. Please choose a different name.',
       DIRECTORY_ALREADY_EXISTS: 'The directory named "$1" already exists. Please choose a different name.',
       ERROR_RENAMING: 'Unable to rename "$1": $2',
       RENAME_PROMPT: 'Enter a new name',
       RENAME_BUTTON_LABEL: 'Rename',
 
       ERROR_DELETING: 'Unable to delete "$1": $2',
       DELETE_BUTTON_LABEL: 'Delete',
@@ skipping 117 matching lines @@
   }
 };
 
 chrome.metricsPrivate = {
   recordMediumCount: function() {},
   recordSmallCount: function() {},
   recordTime: function() {},
   recordUserAction: function() {},
   recordValue: function() {}
 };