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      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 /**
      6  * States that the extension can be in.
      7  */
      8 var StateEnum = {
      9   DISABLED: 'disabled',
     10   DISPLAY: 'display',
     11   SYSTEM: 'system'
     12 };
     13 
     14 /**
     15  * Key used for storing the current state in {localStorage}.
     16  */
     17 var STATE_KEY = 'state';
     18 
     19 /**
     20  * Loads the locally-saved state asynchronously.
     21  * @param {function} callback Callback invoked with the loaded {StateEnum}.
     22  */
     23 function loadSavedState(callback) {
     24   chrome.storage.local.get(STATE_KEY, function(items) {
     25     var savedState = items[STATE_KEY];
     26     for (var key in StateEnum) {
     27       if (savedState == StateEnum[key]) {
     28         callback(savedState);
     29         return;
     30       }
     31     }
     32     callback(StateEnum.DISABLED);
     33   });
     34 }
     35 
     36 /**
     37  * Switches to a new state.
     38  * @param {string} newState New {StateEnum} to use.
     39  */
     40 function setState(newState) {
     41   var imagePrefix = 'night';
     42   var title = '';
     43 
     44   switch (newState) {
     45     case StateEnum.DISABLED:
     46       chrome.power.releaseKeepAwake();
     47       imagePrefix = 'night';
     48       title = chrome.i18n.getMessage('disabledTitle');
     49       break;
     50     case StateEnum.DISPLAY:
     51       chrome.power.requestKeepAwake('display');
     52       imagePrefix = 'day';
     53       title = chrome.i18n.getMessage('displayTitle');
     54       break;
     55     case StateEnum.SYSTEM:
     56       chrome.power.requestKeepAwake('system');
     57       imagePrefix = 'sunset';
     58       title = chrome.i18n.getMessage('systemTitle');
     59       break;
     60     default:
     61       throw 'Invalid state "' + newState + '"';
     62   }
     63 
     64   var items = {};
     65   items[STATE_KEY] = newState;
     66   chrome.storage.local.set(items);
     67 
     68   chrome.browserAction.setIcon({
     69     path: {
     70       '19': 'images/' + imagePrefix + '-19.png',
     71       '38': 'images/' + imagePrefix + '-38.png'
     72     }
     73   });
     74   chrome.browserAction.setTitle({title: title});
     75 }
     76 
     77 chrome.browserAction.onClicked.addListener(function() {
     78   loadSavedState(function(state) {
     79     switch (state) {
     80       case StateEnum.DISABLED:
     81         setState(StateEnum.DISPLAY);
     82         break;
     83       case StateEnum.DISPLAY:
     84         setState(StateEnum.SYSTEM);
     85         break;
     86       case StateEnum.SYSTEM:
     87         setState(StateEnum.DISABLED);
     88         break;
     89       default:
     90         throw 'Invalid state "' + state + '"';
     91     }
     92   });
     93 });
     94 
     95 chrome.runtime.onStartup.addListener(function() {
     96   loadSavedState(function(state) { setState(state); });
     97 });
     98 
     99 chrome.runtime.onInstalled.addListener(function(details) {
    100   loadSavedState(function(state) { setState(state); });
    101 });
    102