Fix #2250, make sendEvent conditional on whether the user has opted-o…

…ut of Telemetry generally

addon/bootstrap.js

@@ -1,4 +1,8 @@
-/* exported startup */
+/* globals Components */
+/* eslint-disable no-unused-vars */
+
+const prefs = Components.classes["@mozilla.org/preferences-service;1"]
+  .getService(Components.interfaces.nsIPrefBranch);
 
 function startup(data, reason) {
   data.webExtension.startup().then((api) => {
@@ -11,4 +15,9 @@ function shutdown(data, reason) {}
 function install(data, reason) {}
 function uninstall(data, reason) {}
 
-function handleMessage() {}
+function handleMessage(msg, sender, sendReply) {
+  if (msg && msg.funcName === "getTelemetryPref") {
+    let enableTelemetry = prefs.getBoolPref("toolkit.telemetry.enabled");
+    sendReply({type: "success", value: enableTelemetry});
+  }
+}

addon/webextension/background/analytics.js

@@ -1,17 +1,28 @@
-/* globals main, auth, catcher, deviceInfo */
+/* globals main, auth, catcher, deviceInfo, browser */
 
 window.analytics = (function () {
   let exports = {};
 
+  let telemetryPrefKnown = false;
+  let telemetryPref;
+
   exports.sendEvent = function (action, label, options) {
+    let eventCategory = "addon";
+    if (! telemetryPrefKnown) {
+      console.warn("sendEvent called before we were able to refresh");
+      return Promise.resolve();
+    }
+    if (! telemetryPref) {
+      console.info(`Cancelled sendEvent ${eventCategory}/${action}/${label || 'none'} ${JSON.stringify(options)}`);
+      return Promise.resolve();
+    }
     if (typeof label == "object" && (! options)) {
       options = label;
       label = undefined;
     }
     options = options || {};
     let di = deviceInfo();
     return new Promise((resolve, reject) => {
-      let eventCategory = "addon";
       let url = main.getBackend() + "/event";
       let req = new XMLHttpRequest();
       req.open("POST", url);
@@ -43,5 +54,17 @@ window.analytics = (function () {
     });
   };
 
+  exports.refreshTelemetryPref = function () {
+    return browser.runtime.sendMessage({funcName: "getTelemetryPref"}).then((result) => {
+      telemetryPrefKnown = true;
+      telemetryPref = result.value;
+    }, (error) => {
+      // If there's an error reading the pref, we should assume that we shouldn't send data
+      telemetryPrefKnown = true;
+      telemetryPref = false;
+      throw error;
+    });
+  };
+
   return exports;
 })();

addon/webextension/background/main.js

@@ -30,10 +30,14 @@ window.main = (function () {
 
   chrome.browserAction.onClicked.addListener(function(tab) {
     if(tab.url.match(/about:(newtab|blank)/i)) {
-      sendEvent("goto-myshots", "about-newtab");
+      catcher.watchPromise(analytics.refreshTelemetryPref().then(() => {
+        sendEvent("goto-myshots", "about-newtab");
+      }));
       chrome.tabs.update({url: backend + "/shots"});
     } else {
-      sendEvent("start-shot", "toolbar-pageshot-button");
+      catcher.watchPromise(analytics.refreshTelemetryPref().then(() => {
+        sendEvent("start-shot", "toolbar-pageshot-button");
+      }));
       catcher.watchPromise(loadSelector());
     }
   });

docs/METRICS.md

@@ -2,6 +2,10 @@
 
 A summary of the metrics Page Shot will record, and what we're looking for in those metrics.
 
+### Opt-out
+
+The add-on reads the Telemetry opt-out preference (`toolkit.telemetry.enabled`) each time the user presses the Page Shot button.  If this preference is false, or if there is any issue trying to fetch the preference, then no data is sent to the Page Shot server.
+
 ### Key Metrics
 
 Key metrics of Page Shot are fairly simple: