Update chrome.power example extension.

This renames some "level" variables to "state" to make it
more clear that they don't directly map to the API's "level"
enum.  It also registers chrome.runtime.onStartup and
chrome.windows.onCreated (to work around onStartup apparently
not firing on Chrome OS) listeners and switches from
localStorage to chrome.storage.local.

BUG=none


Review URL: https://chromiumcodereview.appspot.com/13493019

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@192992 0039d316-1c4b-4281-b951-d872f2087c98

chrome/common/extensions/docs/examples/api/power/background.js

@@ -3,23 +3,18 @@
 // found in the LICENSE file.
 
 /**
- * Available levels of power-saving-overriding.
+ * States that the extension can be in.
  */
-var LevelEnum = {
-  DISABLED: '',
+var StateEnum = {
+  DISABLED: 'disabled',
   DISPLAY: 'display',
   SYSTEM: 'system'
 };
 
 /**
- * Key used for storing the current level in {localStorage}.
+ * Key used for storing the current state in {localStorage}.
  */
-var LEVEL_KEY = 'level';
-
-/**
- * Current {LevelEnum}.
- */
-var currentLevel = LevelEnum.DISABLED;
+var STATE_KEY = 'state';
 
 /**
  * Should the old {chrome.experimental.power} API be used rather than
@@ -28,40 +23,41 @@ var currentLevel = LevelEnum.DISABLED;
 var useOldApi = !chrome.power;
 
 /**
- * Returns the previously-used level.
- * @return {string} Saved {LevelEnum} from local storage.
+ * Loads the locally-saved state asynchronously.
+ * @param {function} callback Callback invoked with the loaded {StateEnum}.
  */
-function getInitialLevel() {
-  if (LEVEL_KEY in localStorage) {
-    var savedLevel = localStorage[LEVEL_KEY];
-    for (var key in LevelEnum) {
-      if (savedLevel == LevelEnum[key]) {
-        return savedLevel;
+function loadSavedState(callback) {
+  chrome.storage.local.get(STATE_KEY, function(items) {
+    var savedState = items[STATE_KEY];
+    for (var key in StateEnum) {
+      if (savedState == StateEnum[key]) {
+        callback(savedState);
+        return;
       }
     }
-  }
-  return LevelEnum.DISABLED;
+    callback(StateEnum.DISABLED);
+  });
 }
 
 /**
- * Switches to a new power-saving-overriding level.
- * @param {string} newLevel New {LevelEnum} to use.
+ * Switches to a new state.
+ * @param {string} newState New {StateEnum} to use.
  */
-function setLevel(newLevel) {
+function setState(newState) {
   var imagePrefix = 'night';
   var title = '';
 
   // The old API doesn't support the "system" level.
-  if (useOldApi && newLevel == LevelEnum.SYSTEM)
-    newLevel = LevelEnum.DISPLAY;
+  if (useOldApi && newState == StateEnum.SYSTEM)
+    newState = StateEnum.DISPLAY;
 
-  switch (newLevel) {
-    case LevelEnum.DISABLED:
+  switch (newState) {
+    case StateEnum.DISABLED:
       (useOldApi ? chrome.experimental.power : chrome.power).releaseKeepAwake();
       imagePrefix = 'night';
       title = chrome.i18n.getMessage('disabledTitle');
       break;
-    case LevelEnum.DISPLAY:
+    case StateEnum.DISPLAY:
       if (useOldApi)
         chrome.experimental.power.requestKeepAwake(function() {});
       else
@@ -69,17 +65,18 @@ function setLevel(newLevel) {
       imagePrefix = 'day';
       title = chrome.i18n.getMessage('displayTitle');
       break;
-    case LevelEnum.SYSTEM:
+    case StateEnum.SYSTEM:
       chrome.power.requestKeepAwake('system');
       imagePrefix = 'sunset';
       title = chrome.i18n.getMessage('systemTitle');
       break;
     default:
-      throw 'Invalid level "' + newLevel + '"';
+      throw 'Invalid state "' + newState + '"';
   }
 
-  currentLevel = newLevel;
-  localStorage[LEVEL_KEY] = currentLevel;
+  var items = {};
+  items[STATE_KEY] = newState;
+  chrome.storage.local.set(items);
 
   chrome.browserAction.setIcon({
     path: {
@@ -90,24 +87,29 @@ function setLevel(newLevel) {
   chrome.browserAction.setTitle({title: title});
 }
 
-/**
- * Cycles levels in response to browser action icon clicks.
- */
-function handleClicked() {
-  switch (currentLevel) {
-    case LevelEnum.DISABLED:
-      setLevel(LevelEnum.DISPLAY);
-      break;
-    case LevelEnum.DISPLAY:
-      setLevel(useOldApi ? LevelEnum.DISABLED : LevelEnum.SYSTEM);
-      break;
-    case LevelEnum.SYSTEM:
-      setLevel(LevelEnum.DISABLED);
-      break;
-    default:
-      throw 'Invalid level "' + currentLevel + '"';
-  }
-}
+chrome.browserAction.onClicked.addListener(function() {
+  loadSavedState(function(state) {
+    switch (state) {
+      case StateEnum.DISABLED:
+        setState(StateEnum.DISPLAY);
+        break;
+      case StateEnum.DISPLAY:
+        setState(useOldApi ? StateEnum.DISABLED : StateEnum.SYSTEM);
+        break;
+      case StateEnum.SYSTEM:
+        setState(StateEnum.DISABLED);
+        break;
+      default:
+        throw 'Invalid state "' + state + '"';
+    }
+  });
+});
+
+chrome.runtime.onStartup.addListener(function() {
+  loadSavedState(function(state) { setState(state); });
+});
 
-chrome.browserAction.onClicked.addListener(handleClicked);
-setLevel(getInitialLevel());
+// TODO(derat): Remove this once http://crbug.com/222473 is fixed.
+chrome.windows.onCreated.addListener(function() {
+  loadSavedState(function(state) { setState(state); });
+});

chrome/common/extensions/docs/examples/api/power/manifest.json

@@ -3,7 +3,7 @@
 
   "name": "__MSG_extensionName__",
   "description": "__MSG_extensionDescription__",
-  "version": "1.4",
+  "version": "1.6",
   "icons": {
     "16": "images/icon-16.png",
     "48": "images/icon-48.png",
@@ -12,7 +12,8 @@
 
   "permissions": [
     "experimental",
-    "power"
+    "power",
+    "storage"
   ],
   "browser_action": {
     "default_title": "__MSG_disabledTitle__",