Update the calculator to use the launch event and transient background pages

chrome/common/extensions/docs/samples.json

 {
   "api": {
     "chrome.bookmarks.create": "bookmarks.html#method-create",
     "chrome.bookmarks.get": "bookmarks.html#method-get",
     "chrome.bookmarks.getChildren": "bookmarks.html#method-getChildren",
     "chrome.bookmarks.getRecent": "bookmarks.html#method-getRecent",
     "chrome.bookmarks.getSubTree": "bookmarks.html#method-getSubTree",
     "chrome.bookmarks.getTree": "bookmarks.html#method-getTree",
     "chrome.bookmarks.move": "bookmarks.html#method-move",
     "chrome.bookmarks.onChanged": "bookmarks.html#event-onChanged",
@@ skipping 601 matching lines @@
       "source_files": [
         "calculator.html",
         "controller.js",
         "jquery\/jquery.min.js",
         "main.js",
         "manifest.json",
         "model.js",
         "style.css",
         "view.js"
       ],
-      "source_hash": "2e68ea5f2524391fea969d11a7e1ff0116d6ecb7",
+      "source_hash": "51200651a807c2c6e365c7b7228373b61ab3230b",
       "zip_path": "examples\/extensions\/calculator.zip"
     },
     {
       "api_calls": [
         "chrome.webRequest.onBeforeRequest"
       ],
       "crx_path": null,
       "description": "I can't has cheezburger!",
       "features": [
         "background_page",
@@ skipping 1993 matching lines @@
         "manifest.json",
         "popup.html",
         "popup.js",
         "sample.css"
       ],
       "source_hash": "8e51dc3a9577065d22ce92f3c838edc5ceaf4e65",
       "zip_path": "examples\/api\/extension\/isAllowedAccess.zip"
     }
   ]
 }