Implement some cross-browser practices (#473)

* Add mozilla plugin key to manifest

* Move all chrome references into platform-checking module

Addresses #453

* Add chrome global back to linter blacklist

* Add tests

3 files changed, 68 insertions, 15 deletions

diff --git a/app/scripts/lib/extension-instance.js b/app/scripts/lib/extension-instance.js
new file mode 100644
index 000000000..eeab6c6d0
--- /dev/null
+++ b/app/scripts/lib/extension-instance.js
@@ -0,0 +1,38 @@
+const apis = [
+  'alarms',
+  'bookmarks',
+  'browserAction',
+  'commands',
+  'contextMenus',
+  'cookies',
+  'downloads',
+  'events',
+  'extension',
+  'extensionTypes',
+  'history',
+  'i18n',
+  'idle',
+  'notifications',
+  'pageAction',
+  'runtime',
+  'storage',
+  'tabs',
+  'webNavigation',
+  'webRequest',
+  'windows',
+]
+
+function Extension () {
+  const _this = this
+  let global = window
+
+  if (window.chrome) {
+    global = window.chrome
+  }
+
+  apis.forEach(function (api) {
+    _this[api] = global[api]
+  })
+}
+
+module.exports = Extension
diff --git a/app/scripts/lib/extension.js b/app/scripts/lib/extension.js
new file mode 100644
index 000000000..4b670490f
--- /dev/null
+++ b/app/scripts/lib/extension.js
@@ -0,0 +1,14 @@
+/* Extension.js
+ *
+ * A module for unifying browser differences in the WebExtension API.
+ *
+ * Initially implemented because Chrome hides all of their WebExtension API
+ * behind a global `chrome` variable, but we'd like to start grooming
+ * the code-base for cross-browser extension support.
+ *
+ * You can read more about the WebExtension API here:
+ * https://developer.mozilla.org/en-US/Add-ons/WebExtensions
+ */
+
+const Extension = require('./extension-instance')
+module.exports = new Extension()
diff --git a/app/scripts/lib/notifications.js b/app/scripts/lib/notifications.js
index b6590b0e5..6c1601df1 100644
--- a/app/scripts/lib/notifications.js
+++ b/app/scripts/lib/notifications.js
@@ -7,6 +7,7 @@ const h = require('react-hyperscript')
 const PendingTxDetails = require('../../../ui/app/components/pending-tx-details')
 const PendingMsgDetails = require('../../../ui/app/components/pending-msg-details')
 const MetaMaskUiCss = require('../../../ui/css')
+const extension = require('./extension')
 var notificationHandlers = {}
 
 const notifications = {
@@ -20,34 +21,34 @@ window.METAMASK_NOTIFIER = notifications
 setupListeners()
 
 function setupListeners () {
-  // guard for chrome bug https://github.com/MetaMask/metamask-plugin/issues/236
-  if (!chrome.notifications) return console.error('Chrome notifications API missing...')
+  // guard for extension bug https://github.com/MetaMask/metamask-plugin/issues/236
+  if (!extension.notifications) return console.error('Chrome notifications API missing...')
 
   // notification button press
-  chrome.notifications.onButtonClicked.addListener(function (notificationId, buttonIndex) {
+  extension.notifications.onButtonClicked.addListener(function (notificationId, buttonIndex) {
     var handlers = notificationHandlers[notificationId]
     if (buttonIndex === 0) {
       handlers.confirm()
     } else {
       handlers.cancel()
     }
-    chrome.notifications.clear(notificationId)
+    extension.notifications.clear(notificationId)
   })
 
   // notification teardown
-  chrome.notifications.onClosed.addListener(function (notificationId) {
+  extension.notifications.onClosed.addListener(function (notificationId) {
     delete notificationHandlers[notificationId]
   })
 }
 
 // creation helper
 function createUnlockRequestNotification (opts) {
-  // guard for chrome bug https://github.com/MetaMask/metamask-plugin/issues/236
-  if (!chrome.notifications) return console.error('Chrome notifications API missing...')
+  // guard for extension bug https://github.com/MetaMask/metamask-plugin/issues/236
+  if (!extension.notifications) return console.error('Chrome notifications API missing...')
   var message = 'An Ethereum app has requested a signature. Please unlock your account.'
 
   var id = createId()
-  chrome.notifications.create(id, {
+  extension.notifications.create(id, {
     type: 'basic',
     iconUrl: '/images/icon-128.png',
     title: opts.title,
@@ -56,8 +57,8 @@ function createUnlockRequestNotification (opts) {
 }
 
 function createTxNotification (state) {
-  // guard for chrome bug https://github.com/MetaMask/metamask-plugin/issues/236
-  if (!chrome.notifications) return console.error('Chrome notifications API missing...')
+  // guard for extension bug https://github.com/MetaMask/metamask-plugin/issues/236
+  if (!extension.notifications) return console.error('Chrome notifications API missing...')
 
   renderTxNotificationSVG(state, function (err, notificationSvgSource) {
     if (err) throw err
@@ -70,8 +71,8 @@ function createTxNotification (state) {
 }
 
 function createMsgNotification (state) {
-  // guard for chrome bug https://github.com/MetaMask/metamask-plugin/issues/236
-  if (!chrome.notifications) return console.error('Chrome notifications API missing...')
+  // guard for extension bug https://github.com/MetaMask/metamask-plugin/issues/236
+  if (!extension.notifications) return console.error('Chrome notifications API missing...')
 
   renderMsgNotificationSVG(state, function (err, notificationSvgSource) {
     if (err) throw err
@@ -84,11 +85,11 @@ function createMsgNotification (state) {
 }
 
 function showNotification (state) {
-  // guard for chrome bug https://github.com/MetaMask/metamask-plugin/issues/236
-  if (!chrome.notifications) return console.error('Chrome notifications API missing...')
+  // guard for extension bug https://github.com/MetaMask/metamask-plugin/issues/236
+  if (!extension.notifications) return console.error('Chrome notifications API missing...')
 
   var id = createId()
-  chrome.notifications.create(id, {
+  extension.notifications.create(id, {
     type: 'image',
     requireInteraction: true,
     iconUrl: '/images/icon-128.png',