Make chrome.power sample extension work across updates.

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

Index: chrome/common/extensions/docs/examples/api/power/background.js
diff --git a/chrome/common/extensions/docs/examples/api/power/background.js b/chrome/common/extensions/docs/examples/api/power/background.js
index 95217c07e1cff3935f8076d3395405f4370340d9..5fd9083b2181e5bd2fd5a470a56838863268045b 100644
--- a/chrome/common/extensions/docs/examples/api/power/background.js
+++ b/chrome/common/extensions/docs/examples/api/power/background.js
@@ -95,3 +95,7 @@ chrome.browserAction.onClicked.addListener(function() {
 chrome.runtime.onStartup.addListener(function() {
   loadSavedState(function(state) { setState(state); });
 });
+
+chrome.runtime.onInstalled.addListener(function(details) {
+  loadSavedState(function(state) { setState(state); });

[Matt Perry, 2014/09/19 19:47:27]

I assume loadSavedState can be called multiple times without a problem. I
mention this because you might get an onInstalled event and onStartup event one
after the other, e.g. when Chrome itself updates.

[Daniel Erat, 2014/09/19 19:53:11]

yep, this should be fine. the locks don't stack and setState() blows away
whatever was there already, so the second duplicated call should just be a
no-op.

+});