ui/file_manager/file_manager/background/js/background.js - platform/external/chromium_org - Git at Google

 // 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.

 /**
  * Type of a Files.app's instance launch.
  * @enum {number}
  */
 var LaunchType = {
   ALWAYS_CREATE: 0,
   FOCUS_ANY_OR_CREATE: 1,
   FOCUS_SAME_OR_CREATE: 2
 };
 Object.freeze(LaunchType);

 /**
  * Root class of the background page.
  * @constructor
  * @extends {BackgroundBase}
  */
 function FileBrowserBackground() {
   BackgroundBase.call(this);

   /**
    * Map of all currently open file dialogs. The key is an app ID.
    * @type {Object.<string, Window>}
    */
   this.dialogs = {};

   /**
    * Synchronous queue for asynchronous calls.
    * @type {AsyncUtil.Queue}
    */
   this.queue = new AsyncUtil.Queue();

   /**
    * Progress center of the background page.
    * @type {ProgressCenter}
    */
   this.progressCenter = new ProgressCenter();

   /**
    * File operation manager.
    * @type {FileOperationManager}
    */
   this.fileOperationManager = new FileOperationManager();

   /**
    * Event handler for progress center.
    * @type {FileOperationHandler}
    * @private
    */
   this.fileOperationHandler_ = new FileOperationHandler(this);

   /**
    * Event handler for C++ sides notifications.
    * @type {DeviceHandler}
    * @private
    */
   this.deviceHandler_ = new DeviceHandler();
   this.deviceHandler_.addEventListener(
       DeviceHandler.VOLUME_NAVIGATION_REQUESTED,
       function(event) {
         this.navigateToVolume_(event.devicePath);
       }.bind(this));

   /**
    * Drive sync handler.
    * @type {DriveSyncHandler}
    * @private
    */
   this.driveSyncHandler_ = new DriveSyncHandler(this.progressCenter);
   this.driveSyncHandler_.addEventListener(
       DriveSyncHandler.COMPLETED_EVENT,
       function() { this.tryClose(); }.bind(this));

   /**
    * Promise of string data.
    * @type {Promise}
    */
   this.stringDataPromise = new Promise(function(fulfill) {
     chrome.fileManagerPrivate.getStrings(fulfill);
   });

   /**
    * String assets.
    * @type {Object.<string, string>}
    */
   this.stringData = null;

   /**
    * Callback list to be invoked after initialization.
    * It turns to null after initialization.
    *
    * @type {Array.<function()>}
    * @private
    */
   this.initializeCallbacks_ = [];

   /**
    * Last time when the background page can close.
    *
    * @type {?number}
    * @private
    */
   this.lastTimeCanClose_ = null;

   // Seal self.
   Object.seal(this);

   // Initialize handlers.
   chrome.fileBrowserHandler.onExecute.addListener(this.onExecute_.bind(this));
   chrome.app.runtime.onLaunched.addListener(this.onLaunched_.bind(this));
   chrome.app.runtime.onRestarted.addListener(this.onRestarted_.bind(this));
   chrome.contextMenus.onClicked.addListener(
       this.onContextMenuClicked_.bind(this));

   this.queue.run(function(callback) {
     this.stringDataPromise.then(function(strings) {
       // Init string data.
       this.stringData = strings;
       loadTimeData.data = strings;

       // Init context menu.
       this.initContextMenu_();

       callback();
     }.bind(this)).catch(function(error) {
       console.error(error.stack || error);
       callback();
     });
   }.bind(this));
 }

 /**
  * A number of delay milliseconds from the first call of tryClose to the actual
  * close action.
  * @type {number}
  * @const
  * @private
  */
 FileBrowserBackground.CLOSE_DELAY_MS_ = 5000;

 FileBrowserBackground.prototype = {
   __proto__: BackgroundBase.prototype
 };

 /**
  * Register callback to be invoked after initialization.
  * If the initialization is already done, the callback is invoked immediately.
  *
  * @param {function()} callback Initialize callback to be registered.
  */
 FileBrowserBackground.prototype.ready = function(callback) {
   this.stringDataPromise.then(callback);
 };

 /**
  * Checks the current condition of background page.
  * @return {boolean} True if the background page is closable, false if not.
  */
 FileBrowserBackground.prototype.canClose = function() {
   // If the file operation is going, the background page cannot close.
   if (this.fileOperationManager.hasQueuedTasks() ||
       this.driveSyncHandler_.syncing) {
     this.lastTimeCanClose_ = null;
     return false;
   }

   var views = chrome.extension.getViews();
   var closing = false;
   for (var i = 0; i < views.length; i++) {
     // If the window that is not the background page itself and it is not
     // closing, the background page cannot close.
     if (views[i] !== window && !views[i].closing) {
       this.lastTimeCanClose_ = null;
       return false;
     }
     closing = closing || views[i].closing;
   }

   // If some windows are closing, or the background page can close but could not
   // 5 seconds ago, We need more time for sure.
   if (closing ||
       this.lastTimeCanClose_ === null ||
       (Date.now() - this.lastTimeCanClose_ <
            FileBrowserBackground.CLOSE_DELAY_MS_)) {
     if (this.lastTimeCanClose_ === null)
       this.lastTimeCanClose_ = Date.now();
     setTimeout(this.tryClose.bind(this), FileBrowserBackground.CLOSE_DELAY_MS_);
     return false;
   }

   // Otherwise we can close the background page.
   return true;
 };

 /**
  * Opens the root directory of the volume in Files.app.
  * @param {string} devicePath Device path to a volume to be opened.
  * @private
  */
 FileBrowserBackground.prototype.navigateToVolume_ = function(devicePath) {
   VolumeManager.getInstance().then(function(volumeManager) {
     var volumeInfoList = volumeManager.volumeInfoList;
     for (var i = 0; i < volumeInfoList.length; i++) {
       if (volumeInfoList.item(i).devicePath == devicePath)
         return volumeInfoList.item(i).resolveDisplayRoot();
     }
     return Promise.reject(
         'Volume having the device path: ' + devicePath + ' is not found.');
   }).then(function(entry) {
     launchFileManager(
         {currentDirectoryURL: entry.toURL()},
         /* App ID */ undefined,
         LaunchType.FOCUS_SAME_OR_CREATE);
   }).catch(function(error) {
     console.error(error.stack || error);
   });
 };

 /**
  * Prefix for the file manager window ID.
  * @type {string}
  * @const
  */
 var FILES_ID_PREFIX = 'files#';

 /**
  * Regexp matching a file manager window ID.
  * @type {RegExp}
  * @const
  */
 var FILES_ID_PATTERN = new RegExp('^' + FILES_ID_PREFIX + '(\\d*)$');

 /**
  * Prefix for the dialog ID.
  * @type {string}
  * @const
  */
 var DIALOG_ID_PREFIX = 'dialog#';

 /**
  * Value of the next file manager window ID.
  * @type {number}
  */
 var nextFileManagerWindowID = 0;

 /**
  * Value of the next file manager dialog ID.
  * @type {number}
  */
 var nextFileManagerDialogID = 0;

 /**
  * File manager window create options.
  * @type {Object}
  * @const
  */
 var FILE_MANAGER_WINDOW_CREATE_OPTIONS = Object.freeze({
   bounds: Object.freeze({
     left: Math.round(window.screen.availWidth * 0.1),
     top: Math.round(window.screen.availHeight * 0.1),
     width: Math.round(window.screen.availWidth * 0.8),
     height: Math.round(window.screen.availHeight * 0.8)
   }),
   minWidth: 480,
   minHeight: 300,
   hidden: true
 });

 /**
  * @param {Object=} opt_appState App state.
  * @param {number=} opt_id Window id.
  * @param {LaunchType=} opt_type Launch type. Default: ALWAYS_CREATE.
  * @param {function(string)=} opt_callback Completion callback with the App ID.
  */
 function launchFileManager(opt_appState, opt_id, opt_type, opt_callback) {
   var type = opt_type || LaunchType.ALWAYS_CREATE;

   // Wait until all windows are created.
   background.queue.run(function(onTaskCompleted) {
     // Check if there is already a window with the same URL. If so, then
     // reuse it instead of opening a new one.
     if (type == LaunchType.FOCUS_SAME_OR_CREATE ||
         type == LaunchType.FOCUS_ANY_OR_CREATE) {
       if (opt_appState) {
         for (var key in background.appWindows) {
           if (!key.match(FILES_ID_PATTERN))
             continue;

           var contentWindow = background.appWindows[key].contentWindow;
           if (!contentWindow.appState)
             continue;

           // Different current directories.
           if (opt_appState.currentDirectoryURL !==
                   contentWindow.appState.currentDirectoryURL) {
             continue;
           }

           // Selection URL specified, and it is different.
           if (opt_appState.selectionURL &&
                   opt_appState.selectionURL !==
                   contentWindow.appState.selectionURL) {
             continue;
           }

           AppWindowWrapper.focusOnDesktop(
               background.appWindows[key], opt_appState.displayedId);
           if (opt_callback)
             opt_callback(key);
           onTaskCompleted();
           return;
         }
       }
     }

     // Focus any window if none is focused. Try restored first.
     if (type == LaunchType.FOCUS_ANY_OR_CREATE) {
       // If there is already a focused window, then finish.
       for (var key in background.appWindows) {
         if (!key.match(FILES_ID_PATTERN))
           continue;

         // The isFocused() method should always be available, but in case
         // Files.app's failed on some error, wrap it with try catch.
         try {
           if (background.appWindows[key].contentWindow.isFocused()) {
             if (opt_callback)
               opt_callback(key);
             onTaskCompleted();
             return;
           }
         } catch (e) {
           console.error(e.message);
         }
       }
       // Try to focus the first non-minimized window.
       for (var key in background.appWindows) {
         if (!key.match(FILES_ID_PATTERN))
           continue;

         if (!background.appWindows[key].isMinimized()) {
           AppWindowWrapper.focusOnDesktop(
               background.appWindows[key], (opt_appState || {}).displayedId);
           if (opt_callback)
             opt_callback(key);
           onTaskCompleted();
           return;
         }
       }
       // Restore and focus any window.
       for (var key in background.appWindows) {
         if (!key.match(FILES_ID_PATTERN))
           continue;

         AppWindowWrapper.focusOnDesktop(
             background.appWindows[key], (opt_appState || {}).displayedId);
         if (opt_callback)
           opt_callback(key);
         onTaskCompleted();
         return;
       }
     }

     // Create a new instance in case of ALWAYS_CREATE type, or as a fallback
     // for other types.

     var id = opt_id || nextFileManagerWindowID;
     nextFileManagerWindowID = Math.max(nextFileManagerWindowID, id + 1);
     var appId = FILES_ID_PREFIX + id;

     var appWindow = new AppWindowWrapper(
         'main.html',
         appId,
         FILE_MANAGER_WINDOW_CREATE_OPTIONS);
     appWindow.launch(opt_appState || {}, false, function() {
       AppWindowWrapper.focusOnDesktop(
           appWindow.rawAppWindow, (opt_appState || {}).displayedId);
       if (opt_callback)
         opt_callback(appId);
       onTaskCompleted();
     });
   });
 }

 /**
  * Registers dialog window to the background page.
  *
  * @param {Window} dialogWindow Window of the dialog.
  */
 function registerDialog(dialogWindow) {
   var id = DIALOG_ID_PREFIX + (nextFileManagerDialogID++);
   background.dialogs[id] = dialogWindow;
   dialogWindow.addEventListener('pagehide', function() {
     delete background.dialogs[id];
   });
 }

 /**
  * Executes a file browser task.
  *
  * @param {string} action Task id.
  * @param {Object} details Details object.
  * @private
  */
 FileBrowserBackground.prototype.onExecute_ = function(action, details) {
   var appState = {
     params: {action: action},
     // It is not allowed to call getParent() here, since there may be
     // no permissions to access it at this stage. Therefore we are passing
     // the selectionURL only, and the currentDirectory will be resolved
     // later.
     selectionURL: details.entries[0].toURL()
   };

   // Every other action opens a Files app window.
   // For mounted devices just focus any Files.app window. The mounted
   // volume will appear on the navigation list.
   launchFileManager(
       appState,
       /* App ID */ undefined,
       LaunchType.FOCUS_SAME_OR_CREATE);
 };

 /**
  * Launches the app.
  * @private
  */
 FileBrowserBackground.prototype.onLaunched_ = function() {
   if (nextFileManagerWindowID == 0) {
     // The app just launched. Remove window state records that are not needed
     // any more.
     chrome.storage.local.get(function(items) {
       for (var key in items) {
         if (items.hasOwnProperty(key)) {
           if (key.match(FILES_ID_PATTERN))
             chrome.storage.local.remove(key);
         }
       }
     });
   }
   launchFileManager(null, undefined, LaunchType.FOCUS_ANY_OR_CREATE);
 };

 /**
  * Restarted the app, restore windows.
  * @private
  */
 FileBrowserBackground.prototype.onRestarted_ = function() {
   // Reopen file manager windows.
   chrome.storage.local.get(function(items) {
     for (var key in items) {
       if (items.hasOwnProperty(key)) {
         var match = key.match(FILES_ID_PATTERN);
         if (match) {
           var id = Number(match[1]);
           try {
             var appState = /** @type {Object} */ (JSON.parse(items[key]));
             launchFileManager(appState, id);
           } catch (e) {
             console.error('Corrupt launch data for ' + id);
           }
         }
       }
     }
   });
 };

 /**
  * Handles clicks on a custom item on the launcher context menu.
  * @param {OnClickData} info Event details.
  * @private
  */
 FileBrowserBackground.prototype.onContextMenuClicked_ = function(info) {
   if (info.menuItemId == 'new-window') {
     // Find the focused window (if any) and use it's current url for the
     // new window. If not found, then launch with the default url.
     for (var key in background.appWindows) {
       try {
         if (background.appWindows[key].contentWindow.isFocused()) {
           var appState = {
             // Do not clone the selection url, only the current directory.
             currentDirectoryURL: background.appWindows[key].contentWindow.
                 appState.currentDirectoryURL
           };
           launchFileManager(appState);
           return;
         }
       } catch (ignore) {
         // The isFocused method may not be defined during initialization.
         // Therefore, wrapped with a try-catch block.
       }
     }

     // Launch with the default URL.
     launchFileManager();
   }
 };

 /**
  * Initializes the context menu. Recreates if already exists.
  * @private
  */
 FileBrowserBackground.prototype.initContextMenu_ = function() {
   try {
     // According to the spec [1], the callback is optional. But no callback
     // causes an error for some reason, so we call it with null-callback to
     // prevent the error. http://crbug.com/353877
     // - [1] https://developer.chrome.com/extensions/contextMenus#method-remove
     chrome.contextMenus.remove('new-window', function() {});
   } catch (ignore) {
     // There is no way to detect if the context menu is already added, therefore
     // try to recreate it every time.
   }
   chrome.contextMenus.create({
     id: 'new-window',
     contexts: ['launcher'],
     title: str('NEW_WINDOW_BUTTON_LABEL')
   });
 };

 /**
  * Singleton instance of Background.
  * @type {FileBrowserBackground}
  */
 window.background = new FileBrowserBackground();
	// 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.

	/**
	* Type of a Files.app's instance launch.
	* @enum {number}
	*/
	var LaunchType = {
	ALWAYS_CREATE: 0,
	FOCUS_ANY_OR_CREATE: 1,
	FOCUS_SAME_OR_CREATE: 2
	};
	Object.freeze(LaunchType);

	/**
	* Root class of the background page.
	* @constructor
	* @extends {BackgroundBase}
	*/
	function FileBrowserBackground() {
	BackgroundBase.call(this);

	/**
	* Map of all currently open file dialogs. The key is an app ID.
	* @type {Object.<string, Window>}
	*/
	this.dialogs = {};

	/**
	* Synchronous queue for asynchronous calls.
	* @type {AsyncUtil.Queue}
	*/
	this.queue = new AsyncUtil.Queue();

	/**
	* Progress center of the background page.
	* @type {ProgressCenter}
	*/
	this.progressCenter = new ProgressCenter();

	/**
	* File operation manager.
	* @type {FileOperationManager}
	*/
	this.fileOperationManager = new FileOperationManager();

	/**
	* Event handler for progress center.
	* @type {FileOperationHandler}
	* @private
	*/
	this.fileOperationHandler_ = new FileOperationHandler(this);

	/**
	* Event handler for C++ sides notifications.
	* @type {DeviceHandler}
	* @private
	*/
	this.deviceHandler_ = new DeviceHandler();
	this.deviceHandler_.addEventListener(
	DeviceHandler.VOLUME_NAVIGATION_REQUESTED,
	function(event) {
	this.navigateToVolume_(event.devicePath);
	}.bind(this));

	/**
	* Drive sync handler.
	* @type {DriveSyncHandler}
	* @private
	*/
	this.driveSyncHandler_ = new DriveSyncHandler(this.progressCenter);
	this.driveSyncHandler_.addEventListener(
	DriveSyncHandler.COMPLETED_EVENT,
	function() { this.tryClose(); }.bind(this));

	/**
	* Promise of string data.
	* @type {Promise}
	*/
	this.stringDataPromise = new Promise(function(fulfill) {
	chrome.fileManagerPrivate.getStrings(fulfill);
	});

	/**
	* String assets.
	* @type {Object.<string, string>}
	*/
	this.stringData = null;

	/**
	* Callback list to be invoked after initialization.
	* It turns to null after initialization.
	*
	* @type {Array.<function()>}
	* @private
	*/
	this.initializeCallbacks_ = [];

	/**
	* Last time when the background page can close.
	*
	* @type {?number}
	* @private
	*/
	this.lastTimeCanClose_ = null;

	// Seal self.
	Object.seal(this);

	// Initialize handlers.
	chrome.fileBrowserHandler.onExecute.addListener(this.onExecute_.bind(this));
	chrome.app.runtime.onLaunched.addListener(this.onLaunched_.bind(this));
	chrome.app.runtime.onRestarted.addListener(this.onRestarted_.bind(this));
	chrome.contextMenus.onClicked.addListener(
	this.onContextMenuClicked_.bind(this));

	this.queue.run(function(callback) {
	this.stringDataPromise.then(function(strings) {
	// Init string data.
	this.stringData = strings;
	loadTimeData.data = strings;

	// Init context menu.
	this.initContextMenu_();

	callback();
	}.bind(this)).catch(function(error) {
	console.error(error.stack \|\| error);
	callback();
	});
	}.bind(this));
	}

	/**
	* A number of delay milliseconds from the first call of tryClose to the actual
	* close action.
	* @type {number}
	* @const
	* @private
	*/
	FileBrowserBackground.CLOSE_DELAY_MS_ = 5000;

	FileBrowserBackground.prototype = {
	__proto__: BackgroundBase.prototype
	};

	/**
	* Register callback to be invoked after initialization.
	* If the initialization is already done, the callback is invoked immediately.
	*
	* @param {function()} callback Initialize callback to be registered.
	*/
	FileBrowserBackground.prototype.ready = function(callback) {
	this.stringDataPromise.then(callback);
	};

	/**
	* Checks the current condition of background page.
	* @return {boolean} True if the background page is closable, false if not.
	*/
	FileBrowserBackground.prototype.canClose = function() {
	// If the file operation is going, the background page cannot close.
	if (this.fileOperationManager.hasQueuedTasks() \|\|
	this.driveSyncHandler_.syncing) {
	this.lastTimeCanClose_ = null;
	return false;
	}

	var views = chrome.extension.getViews();
	var closing = false;
	for (var i = 0; i < views.length; i++) {
	// If the window that is not the background page itself and it is not
	// closing, the background page cannot close.
	if (views[i] !== window && !views[i].closing) {
	this.lastTimeCanClose_ = null;
	return false;
	}
	closing = closing \|\| views[i].closing;
	}

	// If some windows are closing, or the background page can close but could not
	// 5 seconds ago, We need more time for sure.
	if (closing \|\|
	this.lastTimeCanClose_ === null \|\|
	(Date.now() - this.lastTimeCanClose_ <
	FileBrowserBackground.CLOSE_DELAY_MS_)) {
	if (this.lastTimeCanClose_ === null)
	this.lastTimeCanClose_ = Date.now();
	setTimeout(this.tryClose.bind(this), FileBrowserBackground.CLOSE_DELAY_MS_);
	return false;
	}

	// Otherwise we can close the background page.
	return true;
	};

	/**
	* Opens the root directory of the volume in Files.app.
	* @param {string} devicePath Device path to a volume to be opened.
	* @private
	*/
	FileBrowserBackground.prototype.navigateToVolume_ = function(devicePath) {
	VolumeManager.getInstance().then(function(volumeManager) {
	var volumeInfoList = volumeManager.volumeInfoList;
	for (var i = 0; i < volumeInfoList.length; i++) {
	if (volumeInfoList.item(i).devicePath == devicePath)
	return volumeInfoList.item(i).resolveDisplayRoot();
	}
	return Promise.reject(
	'Volume having the device path: ' + devicePath + ' is not found.');
	}).then(function(entry) {
	launchFileManager(
	{currentDirectoryURL: entry.toURL()},
	/* App ID */ undefined,
	LaunchType.FOCUS_SAME_OR_CREATE);
	}).catch(function(error) {
	console.error(error.stack \|\| error);
	});
	};

	/**
	* Prefix for the file manager window ID.
	* @type {string}
	* @const
	*/
	var FILES_ID_PREFIX = 'files#';

	/**
	* Regexp matching a file manager window ID.
	* @type {RegExp}
	* @const
	*/
	var FILES_ID_PATTERN = new RegExp('^' + FILES_ID_PREFIX + '(\\d*)$');

	/**
	* Prefix for the dialog ID.
	* @type {string}
	* @const
	*/
	var DIALOG_ID_PREFIX = 'dialog#';

	/**
	* Value of the next file manager window ID.
	* @type {number}
	*/
	var nextFileManagerWindowID = 0;

	/**
	* Value of the next file manager dialog ID.
	* @type {number}
	*/
	var nextFileManagerDialogID = 0;

	/**
	* File manager window create options.
	* @type {Object}
	* @const
	*/
	var FILE_MANAGER_WINDOW_CREATE_OPTIONS = Object.freeze({
	bounds: Object.freeze({
	left: Math.round(window.screen.availWidth * 0.1),
	top: Math.round(window.screen.availHeight * 0.1),
	width: Math.round(window.screen.availWidth * 0.8),
	height: Math.round(window.screen.availHeight * 0.8)
	}),
	minWidth: 480,
	minHeight: 300,
	hidden: true
	});

	/**
	* @param {Object=} opt_appState App state.
	* @param {number=} opt_id Window id.
	* @param {LaunchType=} opt_type Launch type. Default: ALWAYS_CREATE.
	* @param {function(string)=} opt_callback Completion callback with the App ID.
	*/
	function launchFileManager(opt_appState, opt_id, opt_type, opt_callback) {
	var type = opt_type \|\| LaunchType.ALWAYS_CREATE;

	// Wait until all windows are created.
	background.queue.run(function(onTaskCompleted) {
	// Check if there is already a window with the same URL. If so, then
	// reuse it instead of opening a new one.
	if (type == LaunchType.FOCUS_SAME_OR_CREATE \|\|
	type == LaunchType.FOCUS_ANY_OR_CREATE) {
	if (opt_appState) {
	for (var key in background.appWindows) {
	if (!key.match(FILES_ID_PATTERN))
	continue;

	var contentWindow = background.appWindows[key].contentWindow;
	if (!contentWindow.appState)
	continue;

	// Different current directories.
	if (opt_appState.currentDirectoryURL !==
	contentWindow.appState.currentDirectoryURL) {
	continue;
	}

	// Selection URL specified, and it is different.
	if (opt_appState.selectionURL &&
	opt_appState.selectionURL !==
	contentWindow.appState.selectionURL) {
	continue;
	}

	AppWindowWrapper.focusOnDesktop(
	background.appWindows[key], opt_appState.displayedId);
	if (opt_callback)
	opt_callback(key);
	onTaskCompleted();
	return;
	}
	}
	}

	// Focus any window if none is focused. Try restored first.
	if (type == LaunchType.FOCUS_ANY_OR_CREATE) {
	// If there is already a focused window, then finish.
	for (var key in background.appWindows) {
	if (!key.match(FILES_ID_PATTERN))
	continue;

	// The isFocused() method should always be available, but in case
	// Files.app's failed on some error, wrap it with try catch.
	try {
	if (background.appWindows[key].contentWindow.isFocused()) {
	if (opt_callback)
	opt_callback(key);
	onTaskCompleted();
	return;
	}
	} catch (e) {
	console.error(e.message);
	}
	}
	// Try to focus the first non-minimized window.
	for (var key in background.appWindows) {
	if (!key.match(FILES_ID_PATTERN))
	continue;

	if (!background.appWindows[key].isMinimized()) {
	AppWindowWrapper.focusOnDesktop(
	background.appWindows[key], (opt_appState \|\| {}).displayedId);
	if (opt_callback)
	opt_callback(key);
	onTaskCompleted();
	return;
	}
	}
	// Restore and focus any window.
	for (var key in background.appWindows) {
	if (!key.match(FILES_ID_PATTERN))
	continue;

	AppWindowWrapper.focusOnDesktop(
	background.appWindows[key], (opt_appState \|\| {}).displayedId);
	if (opt_callback)
	opt_callback(key);
	onTaskCompleted();
	return;
	}
	}

	// Create a new instance in case of ALWAYS_CREATE type, or as a fallback
	// for other types.

	var id = opt_id \|\| nextFileManagerWindowID;
	nextFileManagerWindowID = Math.max(nextFileManagerWindowID, id + 1);
	var appId = FILES_ID_PREFIX + id;

	var appWindow = new AppWindowWrapper(
	'main.html',
	appId,
	FILE_MANAGER_WINDOW_CREATE_OPTIONS);
	appWindow.launch(opt_appState \|\| {}, false, function() {
	AppWindowWrapper.focusOnDesktop(
	appWindow.rawAppWindow, (opt_appState \|\| {}).displayedId);
	if (opt_callback)
	opt_callback(appId);
	onTaskCompleted();
	});
	});
	}

	/**
	* Registers dialog window to the background page.
	*
	* @param {Window} dialogWindow Window of the dialog.
	*/
	function registerDialog(dialogWindow) {
	var id = DIALOG_ID_PREFIX + (nextFileManagerDialogID++);
	background.dialogs[id] = dialogWindow;
	dialogWindow.addEventListener('pagehide', function() {
	delete background.dialogs[id];
	});
	}

	/**
	* Executes a file browser task.
	*
	* @param {string} action Task id.
	* @param {Object} details Details object.
	* @private
	*/
	FileBrowserBackground.prototype.onExecute_ = function(action, details) {
	var appState = {
	params: {action: action},
	// It is not allowed to call getParent() here, since there may be
	// no permissions to access it at this stage. Therefore we are passing
	// the selectionURL only, and the currentDirectory will be resolved
	// later.
	selectionURL: details.entries[0].toURL()
	};

	// Every other action opens a Files app window.
	// For mounted devices just focus any Files.app window. The mounted
	// volume will appear on the navigation list.
	launchFileManager(
	appState,
	/* App ID */ undefined,
	LaunchType.FOCUS_SAME_OR_CREATE);
	};

	/**
	* Launches the app.
	* @private
	*/
	FileBrowserBackground.prototype.onLaunched_ = function() {
	if (nextFileManagerWindowID == 0) {
	// The app just launched. Remove window state records that are not needed
	// any more.
	chrome.storage.local.get(function(items) {
	for (var key in items) {
	if (items.hasOwnProperty(key)) {
	if (key.match(FILES_ID_PATTERN))
	chrome.storage.local.remove(key);
	}
	}
	});
	}
	launchFileManager(null, undefined, LaunchType.FOCUS_ANY_OR_CREATE);
	};

	/**
	* Restarted the app, restore windows.
	* @private
	*/
	FileBrowserBackground.prototype.onRestarted_ = function() {
	// Reopen file manager windows.
	chrome.storage.local.get(function(items) {
	for (var key in items) {
	if (items.hasOwnProperty(key)) {
	var match = key.match(FILES_ID_PATTERN);
	if (match) {
	var id = Number(match[1]);
	try {
	var appState = /** @type {Object} */ (JSON.parse(items[key]));
	launchFileManager(appState, id);
	} catch (e) {
	console.error('Corrupt launch data for ' + id);
	}
	}
	}
	}
	});
	};

	/**
	* Handles clicks on a custom item on the launcher context menu.
	* @param {OnClickData} info Event details.
	* @private
	*/
	FileBrowserBackground.prototype.onContextMenuClicked_ = function(info) {
	if (info.menuItemId == 'new-window') {
	// Find the focused window (if any) and use it's current url for the
	// new window. If not found, then launch with the default url.
	for (var key in background.appWindows) {
	try {
	if (background.appWindows[key].contentWindow.isFocused()) {
	var appState = {
	// Do not clone the selection url, only the current directory.
	currentDirectoryURL: background.appWindows[key].contentWindow.
	appState.currentDirectoryURL
	};
	launchFileManager(appState);
	return;
	}
	} catch (ignore) {
	// The isFocused method may not be defined during initialization.
	// Therefore, wrapped with a try-catch block.
	}
	}

	// Launch with the default URL.
	launchFileManager();
	}
	};

	/**
	* Initializes the context menu. Recreates if already exists.
	* @private
	*/
	FileBrowserBackground.prototype.initContextMenu_ = function() {
	try {
	// According to the spec [1], the callback is optional. But no callback
	// causes an error for some reason, so we call it with null-callback to
	// prevent the error. http://crbug.com/353877
	// - [1] https://developer.chrome.com/extensions/contextMenus#method-remove
	chrome.contextMenus.remove('new-window', function() {});
	} catch (ignore) {
	// There is no way to detect if the context menu is already added, therefore
	// try to recreate it every time.
	}
	chrome.contextMenus.create({
	id: 'new-window',
	contexts: ['launcher'],
	title: str('NEW_WINDOW_BUTTON_LABEL')
	});
	};

	/**
	* Singleton instance of Background.
	* @type {FileBrowserBackground}
	*/
	window.background = new FileBrowserBackground();