Fix #157: Add Firefox UI telemetry probes

* Add `visit_supported_site` and `hide_toolbar_button` probes.
  * `hide_toolbar_button` required adding a new experimental API, `customizeUI`, which allows the extension to be notified when the Firefox CustomizeUI module detects the `onWidgetRemoved` event. This event fires any time a widget is removed from the chrome, including browserAction buttons. The widget is identified by a widgetId.
* Update METRICS.md to move `uninstall` probe to Appendix, since it is handled by the Addons Manager's event telemetry already.
* Create a new ./src/telemetry/content.js file to handle sending messages to the background telemetry script to record events from content scripts.

docs/METRICS.md

@@ -261,16 +261,7 @@ Fired when the user clicks an undo button in a Product Card in the browserAction
 
 ### `uninstall`
 
-Fired when the user uninstalls the extension.
-
-#### Payload properties
-
-- `methods`: String
-  - `'uninstall'`
-- `objects`: String
-  - `'uninstall'`
-- `extra_keys`: Object
-  - `'tracked_prods'`
+See Appendix A.
 
 ### `hide_toolbar_button`
 
@@ -381,3 +372,48 @@ No telemetry will be sent from the extension in the following additional cases:
 - The user is in a [Private Browsing](https://support.mozilla.org/en-US/kb/private-browsing-use-firefox-without-history?redirectlocale=en-US&redirectslug=Private+Browsing)  window
   - Preference: `browser.privatebrowsing.autostart`
   - [`windows.Window`](https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/windows/Window) property: `window.incognito`
+
+
+## Appendices
+
+### Appendix A: `uninstall`
+
+Fired when the user uninstalls the extension.
+
+This event, along with all other add-on lifecycle events, is recorded by the Addons Manager's event telemetry in Firefox. It will exist as part of the `main` ping under `payload.processes.parent.events` as an array in the `events` array. This event will be fired under the `addonsManager` telemetry category.
+
+#### Sample Ping
+
+Note: This is a sample ping. The exact value for the extension ID may differ, though the other values are correct.
+
+```javascript
+{
+  "type": "main",
+  // ...
+  "payload": {
+    // ...
+    "processes": {
+      // ...
+      "parent": {
+        // ...
+        "events": [
+          [
+            9792,
+            "addonsManager",
+            "uninstall",
+            "extension",
+            "shopping-testpilot@mozilla.org", // the extension ID
+            {
+              "source": "testpilot"
+              // ...
+            }
+          ]
+        ]
+      }
+      // ...
+    }
+    // ...
+  }
+  // ...
+}
+```

src/background/index.js

@@ -16,7 +16,7 @@ import {handleWebRequest, updatePrices} from 'commerce/background/price_updates'
 import store from 'commerce/state';
 import {checkMigrations} from 'commerce/state/migrations';
 import {loadStateFromStorage} from 'commerce/state/sync';
-import {registerEvents} from 'commerce/telemetry/extension';
+import {registerEvents, handleWidgetRemoved} from 'commerce/telemetry/extension';
 
 (async function main() {
   registerEvents();
@@ -37,6 +37,9 @@ import {registerEvents} from 'commerce/telemetry/extension';
   // Open the product page when an alert notification is clicked.
   browser.notifications.onClicked.addListener(handleNotificationClicked);
 
+  // Record hide_toolbar_button event when the toolbar button is hidden.
+  browser.customizableUI.onWidgetRemoved.addListener(handleWidgetRemoved);
+
   // Enable content scripts now that the background listener is registered.
   // Store the return value globally to avoid destroying it, which would
   // unregister the content scripts.

src/background/messages.js

@@ -19,12 +19,19 @@
 import {handleConfigMessage} from 'commerce/config/background';
 import {handleBrowserActionOpened} from 'commerce/background/browser_action';
 import {handleExtractedProductData} from 'commerce/background/extraction';
+import {recordEvent} from 'commerce/telemetry/extension';
 
 // sendMessage/onMessage handlers
 
 export const messageHandlers = new Map([
   ['extracted-product', handleExtractedProductData],
   ['config', handleConfigMessage],
+  ['telemetry', async message => recordEvent(
+    message.data.method,
+    message.data.object,
+    message.data.value,
+    message.data.extra,
+  )],
 ]);
 
 export async function handleMessage(message, sender) {

src/experiment_apis/customizableUI/api.js

@@ -0,0 +1,31 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+/* global ChromeUtils ExtensionAPI ExtensionCommon */
+
+this.customizableUI = class extends ExtensionAPI {
+  getAPI(context) {
+    ChromeUtils.import('resource://gre/modules/ExtensionCommon.jsm');
+    const {EventManager} = ExtensionCommon;
+    const {CustomizableUI} = ChromeUtils.import('resource:///modules/CustomizableUI.jsm', {});
+    return {
+      customizableUI: {
+        onWidgetRemoved: new EventManager(
+          context,
+          'customizableUI.onWidgetRemoved',
+          (fire) => {
+            const toolbarButton = {
+              onWidgetRemoved(widgetId) {
+                fire.async(widgetId);
+              },
+            };
+            CustomizableUI.addListener(toolbarButton);
+            return () => {
+              CustomizableUI.removeListener(toolbarButton);
+            };
+          },
+        ).api(),
+      },
+    };
+  }
+};

src/experiment_apis/customizableUI/schema.json

@@ -0,0 +1,19 @@
+[
+  {
+    "namespace": "customizableUI",
+    "events": [
+      {
+        "name": "onWidgetRemoved",
+        "type": "function",
+        "description": "Fired when a widget is removed from the browser chrome",
+        "parameters": [
+          {
+            "name": "widgetId",
+            "description": "The unique identifier for the widget",
+            "type": "string"
+          }
+        ]
+      }
+    ]
+  }
+]

src/extraction/index.js

@@ -13,6 +13,7 @@ import extractProductWithFathom from 'commerce/extraction/fathom';
 import extractProductWithFallback from 'commerce/extraction/selector';
 import extractProductWithOpenGraph from 'commerce/extraction/open_graph';
 import {shouldExtract} from 'commerce/privacy';
+import recordEvent from 'commerce/telemetry/content';
 
 /**
  * Extraction methods are given the document object for the page, and must
@@ -89,6 +90,11 @@ async function attemptExtraction() {
     return;
   }
 
+  // Record visit_supported_site event
+  if (!isBackgroundUpdate) {
+    await recordEvent('visit_supported_site', 'supported_site');
+  }
+
   // Extract immediately, and again if the readyState changes.
   let extractedProduct = await attemptExtraction();
   document.addEventListener('readystatechange', async () => {

src/manifest.json

@@ -37,6 +37,14 @@
     "telemetry"
   ],
   "experiment_apis": {
+    "customizableUI": {
+      "schema": "experiment_apis/customizableUI/schema.json",
+      "parent": {
+        "scopes": ["addon_parent"],
+        "script": "experiment_apis/customizableUI/api.js",
+        "paths": [["customizableUI"]]
+      }
+    },
     "shoppingPrefs": {
       "schema": "experiment_apis/shoppingPrefs/schema.json",
       "parent": {

src/telemetry/content.js

@@ -0,0 +1,21 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Communication from content scripts to the background page for recording
+ * telemetry events.
+ * @module
+ */
+
+export default async function recordEvent(method, object, value = null, extra = null) {
+  await browser.runtime.sendMessage({
+    type: 'telemetry',
+    data: {
+      method,
+      object,
+      value,
+      extra,
+    },
+  });
+}

src/telemetry/extension.js

@@ -212,3 +212,14 @@ export async function getBadgeType() {
       return 'unknown';
   }
 }
+
+export async function handleWidgetRemoved(widgetId) {
+  const addonId = (await browser.management.getSelf()).id;
+  // widgetId replaces '@' and '.' in the addonId with _
+  const modifiedAddonId = addonId.replace(/[@.+]/g, '_');
+  if (`${modifiedAddonId}-browser-action` === widgetId) {
+    await recordEvent('hide_toolbar_button', 'toolbar_button', null, {
+      badge_type: await getBadgeType(),
+    });
+  }
+}