Re: #71, webExtension version.

Pattern
- run as background_script
- expect to be webpacked or browsierfied in
- feature telemetry relies on seeing the shield study in the scope.

to be done:
- storage of things
- api to override?
- prefs (as a permission for some addons, specific to each study)
- know that uninstall happened to have finalize.
- actually send telemetry
- actually tag enviroment

webExtension/.gitignore

@@ -0,0 +1 @@
+addon/background_scripts/index.js

webExtension/addon/manifest.json

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+{
+  "description": "Adds a browser action icon to the toolbar.",
+  "manifest_version": 2,
+  "name": "Example Study",
+  "version": "1.0",
+  "browser_action": {
+    "default_title": "Our Feature",
+    "browser_style": true
+  },
+  "background": {
+    "scripts": [
+      "background_scripts/index.js"
+    ]
+  },
+  "web_accessible_resources": [
+    "icons/kittens.jpg",
+    "icons/puppies.jpg"
+  ]
+}

webExtension/feature/index.js

@@ -0,0 +1,25 @@
+/* global study */
+
+
+
+function telemetry (data) {
+  console.log("module telemetry:", data);
+  study.telemetry(data); // we did window.study in the other file
+}
+
+let times = 0;
+function handleClick () {
+  times += 1;
+  console.log('got a click');
+  telemetry({"evt": "click", times: times});
+}
+
+function init(branch) {
+  browser.browserAction.setIcon({path: `icons/${branch}.png`});
+  browser.browserAction.setTitle({title: branch});
+  browser.browserAction.onClicked.addListener(handleClick);
+}
+
+exports.init = init;
+
+

webExtension/ourStudy.js

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+
+const shield = require("./shield-v4.js");
+const feature = require("./feature/")
+const studyConfig = {
+  name: self.id,
+  days: 14,
+  surveyUrls:  {
+    'end-of-study': 'http://example.com/some/url',
+    'user-ended-study': 'http://example.com/some/url',
+    'ineligible':  null
+  }
+}
+
+class ExampleStudy extends shield.ShieldStudy {
+  chooseVariation () {
+    return "kittens";
+  }
+}
+
+// put it up in global, because we are going to webpack
+let study = window.study = new ExampleStudy(studyConfig);
+
+function listenForTelemetryFromContent (request, sender, sendResponse) {
+  console.log(request, sender, sendResponse);
+  if (request.telemetry) {
+    study.telemetry(request.data);
+  }
+}
+
+browser.runtime.onMessage.addListener(listenForTelemetryFromContent);
+
+
+// this is the first time onlye
+if (study.isEligible()) {
+  let variation = study.chooseVariation();
+  study.start();
+  feature.init(variation);
+  telemetryOn();
+}
+
+// other times we need to do other things
+
+
+

webExtension/package.json

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+{
+  "name": "webpack-webextension",
+  "version": "1.0.0",
+  "description": "A minimal example of how to use npm modules from within a WebExtension.",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "build": "webpack"
+  },
+  "license": "MPL-2.0",
+  "devDependencies": {
+    "webpack": "^2.3.2"
+  },
+  "dependencies": {
+    "left-pad": "^1.1.1"
+  }
+}

webExtension/shield-study.js

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+/* shield under web extensions is just a library,
+   MEANT to be webpacked/browserified */
+
+//let study = new SubclassedStudy(config);
+
+class ShieldStudy {
+  constructor (config) {
+    this.config = config;
+  }
+  isEligible () {
+    return true;
+  }
+
+  chooseVariation () {
+    /* do some rng or deterministic magic */
+  }
+
+  stored () {
+    /*firstrun
+    branchname*/
+  }
+
+  isFirstRun () {
+    // can check if we have any local storage?
+    return true;
+  }
+
+  doOnce() {
+  }
+
+  cleanup () {
+    console.log("cleaing up")
+  }
+
+  checkForExpiration () {
+    return false
+  }
+
+  telemetry (...args) {
+    console.log("telemtry sent:", ...args);
+  }
+
+  start () {
+    console.log('starting up!')
+  }
+
+  die (reason) {
+    switch (reason) {
+    case "ineligible":
+    case "uninstall":
+      break;
+    default:
+      break;
+    }
+  }
+  go () {
+    // try to do all the things?
+    /*
+    if this.isFirstRun
+        checkEligible OR DIE
+        pick and else a branch
+      else
+        revive a branch
+
+      finally:
+        mark the experiment branch
+        start the clocks / timers
+        return the branch
+
+        and ask the feature to init it. // not our job
+    */
+  }
+}
+
+class PrefStudy extends ShieldStudy {
+  constructor (config) {
+    // does special thing with the prefs key
+  }
+  isEligible () {
+    /*is the pref set*/
+  }
+}
+
+/*
+
+if (study.eligible()) {
+  study.going().then(()=>
+    yourfeature.startup(study.branch)
+  )
+}
+
+"going" does this:
+  spec stuff:
+  - 1st startup
+    - choose branch once
+    - check eligible
+  - Every startup
+    - re-use branch
+    - init the feature
+*/
+
+exports.ShieldStudy = ShieldStudy;
+exports.PrefStudy = PrefStudy;
+

webExtension/webpack.config.js

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+const path = require("path");
+
+module.exports = {
+    entry: {
+        background_scripts: "./ourStudy.js",
+    },
+    output: {
+        path: path.resolve(__dirname, "addon"),
+        filename: "[name]/index.js"
+    }
+};