[Files.app] Split the JavaScript files into subdirectories: common, background, and foreground

chrome/browser/resources/file_manager/js/util.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.
-
-'use strict';
-
-/**
- * Namespace for utility functions.
- */
-var util = {};
-
-/**
- * Returns a function that console.log's its arguments, prefixed by |msg|.
- *
- * @param {string} msg The message prefix to use in the log.
- * @param {function(...string)=} opt_callback A function to invoke after
- *     logging.
- * @return {function(...string)} Function that logs.
- */
-util.flog = function(msg, opt_callback) {
-  return function() {
-    var ary = Array.apply(null, arguments);
-    console.log(msg + ': ' + ary.join(', '));
-    if (opt_callback)
-      opt_callback.apply(null, arguments);
-  };
-};
-
-/**
- * Returns a function that throws an exception that includes its arguments
- * prefixed by |msg|.
- *
- * @param {string} msg The message prefix to use in the exception.
- * @return {function(...string)} Function that throws.
- */
-util.ferr = function(msg) {
-  return function() {
-    var ary = Array.apply(null, arguments);
-    throw new Error(msg + ': ' + ary.join(', '));
-  };
-};
-
-/**
- * Install a sensible toString() on the FileError object.
- *
- * FileError.prototype.code is a numeric code describing the cause of the
- * error.  The FileError constructor has a named property for each possible
- * error code, but provides no way to map the code to the named property.
- * This toString() implementation fixes that.
- */
-util.installFileErrorToString = function() {
-  FileError.prototype.toString = function() {
-    return '[object FileError: ' + util.getFileErrorMnemonic(this.code) + ']';
-  };
-};
-
-/**
- * @param {number} code The file error code.
- * @return {string} The file error mnemonic.
- */
-util.getFileErrorMnemonic = function(code) {
-  for (var key in FileError) {
-    if (key.search(/_ERR$/) != -1 && FileError[key] == code)
-      return key;
-  }
-
-  return code;
-};
-
-/**
- * @param {number} code File error code (from FileError object).
- * @return {string} Translated file error string.
- */
-util.getFileErrorString = function(code) {
-  for (var key in FileError) {
-    var match = /(.*)_ERR$/.exec(key);
-    if (match && FileError[key] == code) {
-      // This would convert 1 to 'NOT_FOUND'.
-      code = match[1];
-      break;
-    }
-  }
-  console.warn('File error: ' + code);
-  return loadTimeData.getString('FILE_ERROR_' + code) ||
-      loadTimeData.getString('FILE_ERROR_GENERIC');
-};
-
-/**
- * @param {string} str String to escape.
- * @return {string} Escaped string.
- */
-util.htmlEscape = function(str) {
-  return str.replace(/[<>&]/g, function(entity) {
-    switch (entity) {
-      case '<': return '&lt;';
-      case '>': return '&gt;';
-      case '&': return '&amp;';
-    }
-  });
-};
-
-/**
- * @param {string} str String to unescape.
- * @return {string} Unescaped string.
- */
-util.htmlUnescape = function(str) {
-  return str.replace(/&(lt|gt|amp);/g, function(entity) {
-    switch (entity) {
-      case '&lt;': return '<';
-      case '&gt;': return '>';
-      case '&amp;': return '&';
-    }
-  });
-};
-
-/**
- * Iterates the entries contained by dirEntry, and invokes callback once for
- * each entry. On completion, successCallback will be invoked.
- *
- * @param {DirectoryEntry} dirEntry The entry of the directory.
- * @param {function(Entry, function())} callback Invoked for each entry.
- * @param {function()} successCallback Invoked on completion.
- * @param {function(FileError)} errorCallback Invoked if an error is found on
- *     directory entry reading.
- */
-util.forEachDirEntry = function(
-    dirEntry, callback, successCallback, errorCallback) {
-  var reader = dirEntry.createReader();
-  var iterate = function() {
-    reader.readEntries(function(entries) {
-      if (entries.length == 0) {
-        successCallback();
-        return;
-      }
-
-      AsyncUtil.forEach(
-          entries,
-          function(forEachCallback, entry) {
-            // Do not pass index nor entries.
-            callback(entry, forEachCallback);
-          },
-          iterate);
-    }, errorCallback);
-  };
-  iterate();
-};
-
-/**
- * Reads contents of directory.
- * @param {DirectoryEntry} root Root entry.
- * @param {string} path Directory path.
- * @param {function(Array.<Entry>)} callback List of entries passed to callback.
- */
-util.readDirectory = function(root, path, callback) {
-  var onError = function(e) {
-    callback([], e);
-  };
-  root.getDirectory(path, {create: false}, function(entry) {
-    var reader = entry.createReader();
-    var r = [];
-    var readNext = function() {
-      reader.readEntries(function(results) {
-        if (results.length == 0) {
-          callback(r, null);
-          return;
-        }
-        r.push.apply(r, results);
-        readNext();
-      }, onError);
-    };
-    readNext();
-  }, onError);
-};
-
-/**
- * Utility function to resolve multiple directories with a single call.
- *
- * The successCallback will be invoked once for each directory object
- * found.  The errorCallback will be invoked once for each
- * path that could not be resolved.
- *
- * The successCallback is invoked with a null entry when all paths have
- * been processed.
- *
- * @param {DirEntry} dirEntry The base directory.
- * @param {Object} params The parameters to pass to the underlying
- *     getDirectory calls.
- * @param {Array.<string>} paths The list of directories to resolve.
- * @param {function(!DirEntry)} successCallback The function to invoke for
- *     each DirEntry found.  Also invoked once with null at the end of the
- *     process.
- * @param {function(FileError)} errorCallback The function to invoke
- *     for each path that cannot be resolved.
- */
-util.getDirectories = function(dirEntry, params, paths, successCallback,
-                               errorCallback) {
-
-  // Copy the params array, since we're going to destroy it.
-  params = [].slice.call(params);
-
-  var onComplete = function() {
-    successCallback(null);
-  };
-
-  var getNextDirectory = function() {
-    var path = paths.shift();
-    if (!path)
-      return onComplete();
-
-    dirEntry.getDirectory(
-      path, params,
-      function(entry) {
-        successCallback(entry);
-        getNextDirectory();
-      },
-      function(err) {
-        errorCallback(err);
-        getNextDirectory();
-      });
-  };
-
-  getNextDirectory();
-};
-
-/**
- * Utility function to resolve multiple files with a single call.
- *
- * The successCallback will be invoked once for each directory object
- * found.  The errorCallback will be invoked once for each
- * path that could not be resolved.
- *
- * The successCallback is invoked with a null entry when all paths have
- * been processed.
- *
- * @param {DirEntry} dirEntry The base directory.
- * @param {Object} params The parameters to pass to the underlying
- *     getFile calls.
- * @param {Array.<string>} paths The list of files to resolve.
- * @param {function(!FileEntry)} successCallback The function to invoke for
- *     each FileEntry found.  Also invoked once with null at the end of the
- *     process.
- * @param {function(FileError)} errorCallback The function to invoke
- *     for each path that cannot be resolved.
- */
-util.getFiles = function(dirEntry, params, paths, successCallback,
-                         errorCallback) {
-  // Copy the params array, since we're going to destroy it.
-  params = [].slice.call(params);
-
-  var onComplete = function() {
-    successCallback(null);
-  };
-
-  var getNextFile = function() {
-    var path = paths.shift();
-    if (!path)
-      return onComplete();
-
-    dirEntry.getFile(
-      path, params,
-      function(entry) {
-        successCallback(entry);
-        getNextFile();
-      },
-      function(err) {
-        errorCallback(err);
-        getNextFile();
-      });
-  };
-
-  getNextFile();
-};
-
-/**
- * Resolve a path to either a DirectoryEntry or a FileEntry, regardless of
- * whether the path is a directory or file.
- *
- * @param {DirectoryEntry} root The root of the filesystem to search.
- * @param {string} path The path to be resolved.
- * @param {function(Entry)} resultCallback Called back when a path is
- *     successfully resolved. Entry will be either a DirectoryEntry or
- *     a FileEntry.
- * @param {function(FileError)} errorCallback Called back if an unexpected
- *     error occurs while resolving the path.
- */
-util.resolvePath = function(root, path, resultCallback, errorCallback) {
-  if (path == '' || path == '/') {
-    resultCallback(root);
-    return;
-  }
-
-  root.getFile(
-      path, {create: false},
-      resultCallback,
-      function(err) {
-        if (err.code == FileError.TYPE_MISMATCH_ERR) {
-          // Bah.  It's a directory, ask again.
-          root.getDirectory(
-              path, {create: false},
-              resultCallback,
-              errorCallback);
-        } else {
-          errorCallback(err);
-        }
-      });
-};
-
-/**
- * Locate the file referred to by path, creating directories or the file
- * itself if necessary.
- * @param {DirEntry} root The root entry.
- * @param {string} path The file path.
- * @param {function(FileEntry)} successCallback The callback.
- * @param {function(FileError)} errorCallback The callback.
- */
-util.getOrCreateFile = function(root, path, successCallback, errorCallback) {
-  var dirname = null;
-  var basename = null;
-
-  var onDirFound = function(dirEntry) {
-    dirEntry.getFile(basename, { create: true },
-                     successCallback, errorCallback);
-  };
-
-  var i = path.lastIndexOf('/');
-  if (i > -1) {
-    dirname = path.substr(0, i);
-    basename = path.substr(i + 1);
-  } else {
-    basename = path;
-  }
-
-  if (!dirname) {
-    onDirFound(root);
-    return;
-  }
-
-  util.getOrCreateDirectory(root, dirname, onDirFound, errorCallback);
-};
-
-/**
- * Locate the directory referred to by path, creating directories along the
- * way.
- * @param {DirEntry} root The root entry.
- * @param {string} path The directory path.
- * @param {function(FileEntry)} successCallback The callback.
- * @param {function(FileError)} errorCallback The callback.
- */
-util.getOrCreateDirectory = function(root, path, successCallback,
-                                     errorCallback) {
-  var names = path.split('/');
-
-  var getOrCreateNextName = function(dir) {
-    if (!names.length)
-      return successCallback(dir);
-
-    var name;
-    do {
-      name = names.shift();
-    } while (!name || name == '.');
-
-    dir.getDirectory(name, { create: true }, getOrCreateNextName,
-                     errorCallback);
-  };
-
-  getOrCreateNextName(root);
-};
-
-/**
- * Renames the entry to newName.
- * @param {Entry} entry The entry to be renamed.
- * @param {string} newName The new name.
- * @param {function(Entry)} successCallback Callback invoked when the rename
- *     is successfully done.
- * @param {function(FileError)} errorCallback Callback invoked when an error
- *     is found.
- */
-util.rename = function(entry, newName, successCallback, errorCallback) {
-  entry.getParent(function(parent) {
-    // Before moving, we need to check if there is an existing entry at
-    // parent/newName, since moveTo will overwrite it.
-    // Note that this way has some timing issue. After existing check,
-    // a new entry may be create on background. However, there is no way not to
-    // overwrite the existing file, unfortunately. The risk should be low,
-    // assuming the unsafe period is very short.
-    (entry.isFile ? parent.getFile : parent.getDirectory).call(
-        parent, newName, {create: false},
-        function(entry) {
-          // The entry with the name already exists.
-          errorCallback(util.createFileError(FileError.PATH_EXISTS_ERR));
-        },
-        function(error) {
-          if (error.code != FileError.NOT_FOUND_ERR) {
-            // Unexpected error is found.
-            errorCallback(error);
-            return;
-          }
-
-          // No existing entry is found.
-          entry.moveTo(parent, newName, successCallback, errorCallback);
-        });
-  }, errorCallback);
-};
-
-/**
- * Remove a file or a directory.
- * @param {Entry} entry The entry to remove.
- * @param {function()} onSuccess The success callback.
- * @param {function(FileError)} onError The error callback.
- */
-util.removeFileOrDirectory = function(entry, onSuccess, onError) {
-  if (entry.isDirectory)
-    entry.removeRecursively(onSuccess, onError);
-  else
-    entry.remove(onSuccess, onError);
-};
-
-/**
- * Checks if an entry exists at |relativePath| in |dirEntry|.
- * If exists, tries to deduplicate the path by inserting parenthesized number,
- * such as " (1)", before the extension. If it still exists, tries the
- * deduplication again by increasing the number up to 10 times.
- * For example, suppose "file.txt" is given, "file.txt", "file (1).txt",
- * "file (2).txt", ..., "file (9).txt" will be tried.
- *
- * @param {DirectoryEntry} dirEntry The target directory entry.
- * @param {string} relativePath The path to be deduplicated.
- * @param {function(string)} onSuccess Called with the deduplicated path on
- *     success.
- * @param {function(FileError)} onError Called on error.
- */
-util.deduplicatePath = function(dirEntry, relativePath, onSuccess, onError) {
-  // The trial is up to 10.
-  var MAX_RETRY = 10;
-
-  // Crack the path into three part. The parenthesized number (if exists) will
-  // be replaced by incremented number for retry. For example, suppose
-  // |relativePath| is "file (10).txt", the second check path will be
-  // "file (11).txt".
-  var match = /^(.*?)(?: \((\d+)\))?(\.[^.]*?)?$/.exec(relativePath);
-  var prefix = match[1];
-  var copyNumber = match[2] ? parseInt(match[2], 10) : 0;
-  var ext = match[3] ? match[3] : '';
-
-  // The path currently checking the existence.
-  var trialPath = relativePath;
-
-  var onNotResolved = function(err) {
-    // We expect to be unable to resolve the target file, since we're going
-    // to create it during the copy.  However, if the resolve fails with
-    // anything other than NOT_FOUND, that's trouble.
-    if (err.code != FileError.NOT_FOUND_ERR) {
-      onError(err);
-      return;
-    }
-
-    // Found a path that doesn't exist.
-    onSuccess(trialPath);
-  }
-
-  var numRetry = MAX_RETRY;
-  var onResolved = function(entry) {
-    if (--numRetry == 0) {
-      // Hit the limit of the number of retrial.
-      // Note that we cannot create FileError object directly, so here we use
-      // Object.create instead.
-      onError(util.createFileError(FileError.PATH_EXISTS_ERR));
-      return;
-    }
-
-    ++copyNumber;
-    trialPath = prefix + ' (' + copyNumber + ')' + ext;
-    util.resolvePath(dirEntry, trialPath, onResolved, onNotResolved);
-  };
-
-  // Check to see if the target exists.
-  util.resolvePath(dirEntry, trialPath, onResolved, onNotResolved);
-};
-
-/**
- * Convert a number of bytes into a human friendly format, using the correct
- * number separators.
- *
- * @param {number} bytes The number of bytes.
- * @return {string} Localized string.
- */
-util.bytesToString = function(bytes) {
-  // Translation identifiers for size units.
-  var UNITS = ['SIZE_BYTES',
-               'SIZE_KB',
-               'SIZE_MB',
-               'SIZE_GB',
-               'SIZE_TB',
-               'SIZE_PB'];
-
-  // Minimum values for the units above.
-  var STEPS = [0,
-               Math.pow(2, 10),
-               Math.pow(2, 20),
-               Math.pow(2, 30),
-               Math.pow(2, 40),
-               Math.pow(2, 50)];
-
-  var str = function(n, u) {
-    // TODO(rginda): Switch to v8Locale's number formatter when it's
-    // available.
-    return strf(u, n.toLocaleString());
-  };
-
-  var fmt = function(s, u) {
-    var rounded = Math.round(bytes / s * 10) / 10;
-    return str(rounded, u);
-  };
-
-  // Less than 1KB is displayed like '80 bytes'.
-  if (bytes < STEPS[1]) {
-    return str(bytes, UNITS[0]);
-  }
-
-  // Up to 1MB is displayed as rounded up number of KBs.
-  if (bytes < STEPS[2]) {
-    var rounded = Math.ceil(bytes / STEPS[1]);
-    return str(rounded, UNITS[1]);
-  }
-
-  // This loop index is used outside the loop if it turns out |bytes|
-  // requires the largest unit.
-  var i;
-
-  for (i = 2 /* MB */; i < UNITS.length - 1; i++) {
-    if (bytes < STEPS[i + 1])
-      return fmt(STEPS[i], UNITS[i]);
-  }
-
-  return fmt(STEPS[i], UNITS[i]);
-};
-
-/**
- * Utility function to read specified range of bytes from file
- * @param {File} file The file to read.
- * @param {number} begin Starting byte(included).
- * @param {number} end Last byte(excluded).
- * @param {function(File, Uint8Array)} callback Callback to invoke.
- * @param {function(FileError)} onError Error handler.
- */
-util.readFileBytes = function(file, begin, end, callback, onError) {
-  var fileReader = new FileReader();
-  fileReader.onerror = onError;
-  fileReader.onloadend = function() {
-    callback(file, new ByteReader(fileReader.result));
-  };
-  fileReader.readAsArrayBuffer(file.slice(begin, end));
-};
-
-/**
- * Write a blob to a file.
- * Truncates the file first, so the previous content is fully overwritten.
- * @param {FileEntry} entry File entry.
- * @param {Blob} blob The blob to write.
- * @param {function(Event)} onSuccess Completion callback. The first argument is
- *     a 'writeend' event.
- * @param {function(FileError)} onError Error handler.
- */
-util.writeBlobToFile = function(entry, blob, onSuccess, onError) {
-  var truncate = function(writer) {
-    writer.onerror = onError;
-    writer.onwriteend = write.bind(null, writer);
-    writer.truncate(0);
-  };
-
-  var write = function(writer) {
-    writer.onwriteend = onSuccess;
-    writer.write(blob);
-  };
-
-  entry.createWriter(truncate, onError);
-};
-
-/**
- * Returns a string '[Ctrl-][Alt-][Shift-][Meta-]' depending on the event
- * modifiers. Convenient for writing out conditions in keyboard handlers.
- *
- * @param {Event} event The keyboard event.
- * @return {string} Modifiers.
- */
-util.getKeyModifiers = function(event) {
-  return (event.ctrlKey ? 'Ctrl-' : '') +
-         (event.altKey ? 'Alt-' : '') +
-         (event.shiftKey ? 'Shift-' : '') +
-         (event.metaKey ? 'Meta-' : '');
-};
-
-/**
- * @param {HTMLElement} element Element to transform.
- * @param {Object} transform Transform object,
- *                           contains scaleX, scaleY and rotate90 properties.
- */
-util.applyTransform = function(element, transform) {
-  element.style.webkitTransform =
-      transform ? 'scaleX(' + transform.scaleX + ') ' +
-                  'scaleY(' + transform.scaleY + ') ' +
-                  'rotate(' + transform.rotate90 * 90 + 'deg)' :
-      '';
-};
-
-/**
- * Makes filesystem: URL from the path.
- * @param {string} path File or directory path.
- * @return {string} URL.
- */
-util.makeFilesystemUrl = function(path) {
-  path = path.split('/').map(encodeURIComponent).join('/');
-  var prefix = 'external';
-  return 'filesystem:' + document.location.origin + '/' + prefix + path;
-};
-
-/**
- * Extracts path from filesystem: URL.
- * @param {string} url Filesystem URL.
- * @return {string} The path.
- */
-util.extractFilePath = function(url) {
-  var match =
-      /^filesystem:[\w-]*:\/\/[\w]*\/(external|persistent|temporary)(\/.*)$/.
-      exec(url);
-  var path = match && match[2];
-  if (!path) return null;
-  return decodeURIComponent(path);
-};
-
-/**
- * Traverses a directory tree whose root is the given entry, and invokes
- * callback for each entry. Upon completion, successCallback will be called.
- * On error, errorCallback will be called.
- *
- * @param {Entry} entry The root entry.
- * @param {function(Entry):boolean} callback Callback invoked for each entry.
- *     If this returns false, entries under it won't be traversed. Note that
- *     its siblings (and their children) will be still traversed.
- * @param {function()} successCallback Called upon successful completion.
- * @param {function(error)} errorCallback Called upon error.
- */
-util.traverseTree = function(entry, callback, successCallback, errorCallback) {
-  if (!callback(entry)) {
-    successCallback();
-    return;
-  }
-
-  util.forEachDirEntry(
-      entry,
-      function(child, iterationCallback) {
-        util.traverseTree(child, callback, iterationCallback, errorCallback);
-      },
-      successCallback,
-      errorCallback);
-};
-
-/**
- * A shortcut function to create a child element with given tag and class.
- *
- * @param {HTMLElement} parent Parent element.
- * @param {string=} opt_className Class name.
- * @param {string=} opt_tag Element tag, DIV is omitted.
- * @return {Element} Newly created element.
- */
-util.createChild = function(parent, opt_className, opt_tag) {
-  var child = parent.ownerDocument.createElement(opt_tag || 'div');
-  if (opt_className)
-    child.className = opt_className;
-  parent.appendChild(child);
-  return child;
-};
-
-/**
- * Update the app state.
- *
- * @param {string} path Path to be put in the address bar after the hash.
- *   If null the hash is left unchanged.
- * @param {string|Object=} opt_param Search parameter. Used directly if string,
- *   stringified if object. If omitted the search query is left unchanged.
- */
-util.updateAppState = function(path, opt_param) {
-  window.appState = window.appState || {};
-  if (typeof opt_param == 'string')
-    window.appState.params = {};
-  else if (typeof opt_param == 'object')
-    window.appState.params = opt_param;
-  if (path)
-    window.appState.defaultPath = path;
-  util.saveAppState();
-  return;
-};
-
-/**
- * Return a translated string.
- *
- * Wrapper function to make dealing with translated strings more concise.
- * Equivalent to loadTimeData.getString(id).
- *
- * @param {string} id The id of the string to return.
- * @return {string} The translated string.
- */
-function str(id) {
-  return loadTimeData.getString(id);
-}
-
-/**
- * Return a translated string with arguments replaced.
- *
- * Wrapper function to make dealing with translated strings more concise.
- * Equivalent to loadTimeData.getStringF(id, ...).
- *
- * @param {string} id The id of the string to return.
- * @param {...string} var_args The values to replace into the string.
- * @return {string} The translated string with replaced values.
- */
-function strf(id, var_args) {
-  return loadTimeData.getStringF.apply(loadTimeData, arguments);
-}
-
-/**
- * Adapter object that abstracts away the the difference between Chrome app APIs
- * v1 and v2. Is only necessary while the migration to v2 APIs is in progress.
- * TODO(mtomasz): Clean up this. crbug.com/240606.
- */
-util.platform = {
-  /**
-   * @return {boolean} True if Files.app is running as an open files or a select
-   *     folder dialog. False otherwise.
-   */
-  runningInBrowser: function() {
-    return !window.appID;
-  },
-
-  /**
-   * @param {function(Object)} callback Function accepting a preference map.
-   */
-  getPreferences: function(callback) {
-    chrome.storage.local.get(callback);
-  },
-
-  /**
-   * @param {string} key Preference name.
-   * @param {function(string)} callback Function accepting the preference value.
-   */
-  getPreference: function(key, callback) {
-    chrome.storage.local.get(key, function(items) {
-      callback(items[key]);
-    });
-  },
-
-  /**
-   * @param {string} key Preference name.
-   * @param {string|Object} value Preference value.
-   * @param {function()=} opt_callback Completion callback.
-   */
-  setPreference: function(key, value, opt_callback) {
-    if (typeof value != 'string')
-      value = JSON.stringify(value);
-
-    var items = {};
-    items[key] = value;
-    chrome.storage.local.set(items, opt_callback);
-  }
-};
-
-/**
- * Attach page load handler.
- * @param {function()} handler Application-specific load handler.
- */
-util.addPageLoadHandler = function(handler) {
-  document.addEventListener('DOMContentLoaded', function() {
-    handler();
-  });
-};
-
-/**
- * Save app launch data to the local storage.
- */
-util.saveAppState = function() {
-  if (window.appState)
-    util.platform.setPreference(window.appID, window.appState);
-};
-
-/**
- *  AppCache is a persistent timestamped key-value storage backed by
- *  HTML5 local storage.
- *
- *  It is not designed for frequent access. In order to avoid costly
- *  localStorage iteration all data is kept in a single localStorage item.
- *  There is no in-memory caching, so concurrent access is _almost_ safe.
- *
- *  TODO(kaznacheev) Reimplement this based on Indexed DB.
- */
-util.AppCache = function() {};
-
-/**
- * Local storage key.
- */
-util.AppCache.KEY = 'AppCache';
-
-/**
- * Max number of items.
- */
-util.AppCache.CAPACITY = 100;
-
-/**
- * Default lifetime.
- */
-util.AppCache.LIFETIME = 30 * 24 * 60 * 60 * 1000;  // 30 days.
-
-/**
- * @param {string} key Key.
- * @param {function(number)} callback Callback accepting a value.
- */
-util.AppCache.getValue = function(key, callback) {
-  util.AppCache.read_(function(map) {
-    var entry = map[key];
-    callback(entry && entry.value);
-  });
-};
-
-/**
- * Update the cache.
- *
- * @param {string} key Key.
- * @param {string} value Value. Remove the key if value is null.
- * @param {number=} opt_lifetime Maximum time to keep an item (in milliseconds).
- */
-util.AppCache.update = function(key, value, opt_lifetime) {
-  util.AppCache.read_(function(map) {
-    if (value != null) {
-      map[key] = {
-        value: value,
-        expire: Date.now() + (opt_lifetime || util.AppCache.LIFETIME)
-      };
-    } else if (key in map) {
-      delete map[key];
-    } else {
-      return;  // Nothing to do.
-    }
-    util.AppCache.cleanup_(map);
-    util.AppCache.write_(map);
-  });
-};
-
-/**
- * @param {function(Object)} callback Callback accepting a map of timestamped
- *   key-value pairs.
- * @private
- */
-util.AppCache.read_ = function(callback) {
-  util.platform.getPreference(util.AppCache.KEY, function(json) {
-    if (json) {
-      try {
-        callback(JSON.parse(json));
-      } catch (e) {
-        // The local storage item somehow got messed up, start fresh.
-      }
-    }
-    callback({});
-  });
-};
-
-/**
- * @param {Object} map A map of timestamped key-value pairs.
- * @private
- */
-util.AppCache.write_ = function(map) {
-  util.platform.setPreference(util.AppCache.KEY, JSON.stringify(map));
-};
-
-/**
- * Remove over-capacity and obsolete items.
- *
- * @param {Object} map A map of timestamped key-value pairs.
- * @private
- */
-util.AppCache.cleanup_ = function(map) {
-  // Sort keys by ascending timestamps.
-  var keys = [];
-  for (var key in map) {
-    if (map.hasOwnProperty(key))
-      keys.push(key);
-  }
-  keys.sort(function(a, b) { return map[a].expire > map[b].expire });
-
-  var cutoff = Date.now();
-
-  var obsolete = 0;
-  while (obsolete < keys.length &&
-         map[keys[obsolete]].expire < cutoff) {
-    obsolete++;
-  }
-
-  var overCapacity = Math.max(0, keys.length - util.AppCache.CAPACITY);
-
-  var itemsToDelete = Math.max(obsolete, overCapacity);
-  for (var i = 0; i != itemsToDelete; i++) {
-    delete map[keys[i]];
-  }
-};
-
-/**
- * Load an image.
- *
- * @param {Image} image Image element.
- * @param {string} url Source url.
- * @param {Object=} opt_options Hash array of options, eg. width, height,
- *     maxWidth, maxHeight, scale, cache.
- * @param {function()=} opt_isValid Function returning false iff the task
- *     is not valid and should be aborted.
- * @return {?number} Task identifier or null if fetched immediately from
- *     cache.
- */
-util.loadImage = function(image, url, opt_options, opt_isValid) {
-  return ImageLoaderClient.loadToImage(url,
-                                      image,
-                                      opt_options || {},
-                                      function() {},
-                                      function() { image.onerror(); },
-                                      opt_isValid);
-};
-
-/**
- * Cancels loading an image.
- * @param {number} taskId Task identifier returned by util.loadImage().
- */
-util.cancelLoadImage = function(taskId) {
-  ImageLoaderClient.getInstance().cancel(taskId);
-};
-
-/**
- * Finds proerty descriptor in the object prototype chain.
- * @param {Object} object The object.
- * @param {string} propertyName The property name.
- * @return {Object} Property descriptor.
- */
-util.findPropertyDescriptor = function(object, propertyName) {
-  for (var p = object; p; p = Object.getPrototypeOf(p)) {
-    var d = Object.getOwnPropertyDescriptor(p, propertyName);
-    if (d)
-      return d;
-  }
-  return null;
-};
-
-/**
- * Calls inherited property setter (useful when property is
- * overriden).
- * @param {Object} object The object.
- * @param {string} propertyName The property name.
- * @param {*} value Value to set.
- */
-util.callInheritedSetter = function(object, propertyName, value) {
-  var d = util.findPropertyDescriptor(Object.getPrototypeOf(object),
-                                      propertyName);
-  d.set.call(object, value);
-};
-
-/**
- * Returns true if the board of the device matches the given prefix.
- * @param {string} boardPrefix The board prefix to match against.
- *     (ex. "x86-mario". Prefix is used as the actual board name comes with
- *     suffix like "x86-mario-something".
- * @return {boolean} True if the board of the device matches the given prefix.
- */
-util.boardIs = function(boardPrefix) {
-  // The board name should be lower-cased, but making it case-insensitive for
-  // backward compatibility just in case.
-  var board = str('CHROMEOS_RELEASE_BOARD');
-  var pattern = new RegExp('^' + boardPrefix, 'i');
-  return board.match(pattern) != null;
-};
-
-/**
- * Adds an isFocused method to the current window object.
- */
-util.addIsFocusedMethod = function() {
-  var focused = true;
-
-  window.addEventListener('focus', function() {
-    focused = true;
-  });
-
-  window.addEventListener('blur', function() {
-    focused = false;
-  });
-
-  /**
-   * @return {boolean} True if focused.
-   */
-  window.isFocused = function() {
-    return focused;
-  };
-};
-
-/**
- * Makes a redirect to the specified Files.app's window from another window.
- * @param {number} id Window id.
- * @param {string} url Target url.
- * @return {boolean} True if the window has been found. False otherwise.
- */
-util.redirectMainWindow = function(id, url) {
-  // TODO(mtomasz): Implement this for Apps V2, once the photo importer is
-  // restored.
-  return false;
-};
-
-/**
- * Checks, if the Files.app's window is in a full screen mode.
- *
- * @param {AppWindow} appWindow App window to be maximized.
- * @return {boolean} True if the full screen mode is enabled.
- */
-util.isFullScreen = function(appWindow) {
-  if (appWindow) {
-    return appWindow.isFullscreen();
-  } else {
-    console.error('App window not passed. Unable to check status of ' +
-                  'the full screen mode.');
-    return false;
-  }
-};
-
-/**
- * Toggles the full screen mode.
- *
- * @param {AppWindow} appWindow App window to be maximized.
- * @param {boolean} enabled True for enabling, false for disabling.
- */
-util.toggleFullScreen = function(appWindow, enabled) {
-  if (appWindow) {
-    if (enabled)
-      appWindow.fullscreen();
-    else
-      appWindow.restore();
-    return;
-  }
-
-  console.error(
-      'App window not passed. Unable to toggle the full screen mode.');
-};
-
-/**
- * The type of a file operation.
- * @enum {string}
- */
-util.FileOperationType = {
-  COPY: 'COPY',
-  MOVE: 'MOVE',
-  ZIP: 'ZIP',
-};
-
-/**
- * The type of a file operation error.
- * @enum {number}
- */
-util.FileOperationErrorType = {
-  UNEXPECTED_SOURCE_FILE: 0,
-  TARGET_EXISTS: 1,
-  FILESYSTEM_ERROR: 2,
-};
-
-/**
- * The kind of an entry changed event.
- * @enum {number}
- */
-util.EntryChangedKind = {
-  CREATED: 0,
-  DELETED: 1,
-};
-
-/**
- * @param {DirectoryEntry|Object} entry DirectoryEntry to be checked.
- * @return {boolean} True if the given entry is fake.
- */
-util.isFakeDirectoryEntry = function(entry) {
-  // Currently, fake entry doesn't support createReader.
-  return !('createReader' in entry);
-};
-
-/**
- * Creates a FileError instance with given code.
- * Note that we cannot create FileError instance by "new FileError(code)",
- * unfortunately, so here we use Object.create.
- * @param {number} code Error code for the FileError.
- * @return {FileError} FileError instance
- */
-util.createFileError = function(code) {
-  return Object.create(FileError.prototype, {
-    code: { get: function() { return code; } }
-  });
-};
-
-/**
- * @param {Entry|Object} entry1 The entry to be compared. Can be a fake.
- * @param {Entry|Object} entry2 The entry to be compared. Can be a fake.
- * @return {boolean} True if the both entry represents a same file or directory.
- */
-util.isSameEntry = function(entry1, entry2) {
-  // Currently, we can assume there is only one root.
-  // When we support multi-file system, we need to look at filesystem, too.
-  return entry1 === null ? entry2 === null : entry1.fullPath == entry2.fullPath;
-};
-
-/**
- * @param {Entry|Object} parent The parent entry. Can be a fake.
- * @param {Entry|Object} child The child entry. Can be a fake.
- * @return {boolean} True if parent entry is actualy the parent of the child
- *     entry.
- */
-util.isParentEntry = function(parent, child) {
-  // Currently, we can assume there is only one root.
-  // When we support multi-file system, we need to look at filesystem, too.
-  return PathUtil.isParentPath(parent.fullPath, child.fullPath);
-};
-
-/**
- * Views files in the browser.
- *
- * @param {Array.<string>} urls URLs of files to view.
- * @param {function(bool)} callback Callback notifying success or not.
- */
-util.viewFilesInBrowser = function(urls, callback) {
-  var taskId = chrome.runtime.id + '|file|view-in-browser';
-  chrome.fileBrowserPrivate.executeTask(taskId, urls, callback);
-};
-
-/**
- * Visit the URL.
- *
- * If the browser is opening, the url is opened in a new tag, otherwise the url
- * is opened in a new window.
- *
- * @param {string} url URL to visit.
- */
-util.visitURL = function(url) {
-  var params = {url: url};
-  chrome.tabs.create(params, function() {
-    if (chrome.runtime.lastError)
-      chrome.windows.create(params);
-  });
-};
-
-/**
- * Returns normalized current locale, or default locale - 'en'.
- * @return {string} Current locale
- */
-util.getCurrentLocaleOrDefault = function() {
-  // chrome.i18n.getMessage('@@ui_locale') can't be used in packed app.
-  // Instead, we pass it from C++-side with strings.
-  return str('UI_LOCALE') || 'en';
-};
-
-/**
- * Error type of VolumeManager.
- * @enum {string}
- */
-util.VolumeError = Object.freeze({
-  /* Internal errors */
-  NOT_MOUNTED: 'not_mounted',
-  TIMEOUT: 'timeout',
-
-  /* System events */
-  UNKNOWN: 'error_unknown',
-  INTERNAL: 'error_internal',
-  UNKNOWN_FILESYSTEM: 'error_unknown_filesystem',
-  UNSUPPORTED_FILESYSTEM: 'error_unsupported_filesystem',
-  INVALID_ARCHIVE: 'error_invalid_archive',
-  AUTHENTICATION: 'error_authentication',
-  PATH_UNMOUNTED: 'error_path_unmounted'
-});
-
-/**
- * List of connection types of drive.
- *
- * Keep this in sync with the kDriveConnectionType* constants in
- * file_browser_private_api.cc.
- *
- * @enum {string}
- */
-util.DriveConnectionType = Object.freeze({
-  OFFLINE: 'offline',  // Connection is offline or drive is unavailable.
-  METERED: 'metered',  // Connection is metered. Should limit traffic.
-  ONLINE: 'online'     // Connection is online.
-});
-
-/**
- * List of reasons of DriveConnectionType.
- *
- * Keep this in sync with the kDriveConnectionReason constants in
- * file_browser_private_api.cc.
- *
- * @enum {string}
- */
-util.DriveConnectionReason = Object.freeze({
-  NOT_READY: 'not_ready',    // Drive is not ready or authentication is failed.
-  NO_NETWORK: 'no_network',  // Network connection is unavailable.
-  NO_SERVICE: 'no_service'   // Drive service is unavailable.
-});
-
-/**
- * The type of each volume.
- * @enum {string}
- */
-util.VolumeType = Object.freeze({
-  DRIVE: 'drive',
-  DOWNLOADS: 'downloads',
-  REMOVABLE: 'removable',
-  ARCHIVE: 'archive'
-});