feat: Use WebExtension synced storage

Extension settings are saved in synced storage.

- Add storage permission to manifest
- Refactor db.js to use storage.sync api via webextension-polyfill
- Refactor most storage usage and browser messaging to use promise format
- Refactor GA storage usage to promises, stop sending settings. Stopped sending settings becaues the data is not really in a reportable format. This may be handled in #1292.
- Refactor DB message-handling to background page. We cannot have more than one message handler taking the same messages; it breaks everything.
- Reduce storage access when using default project
- Add method to retrieve multiple storage values at once

Closes #1296.

.eslintrc.js

@@ -23,7 +23,7 @@ module.exports = {
   },
   overrides: [
     {
-      files: ['src/scripts/*.js'],
+      files: ['src/scripts/**/*.js'],
       globals: {
         db: false,
         togglbutton: false,

package.json

@@ -68,6 +68,7 @@
     "lint-staged": "^8.1.0",
     "nanoid": "1.2.6",
     "semantic-release": "^15.13.3",
+    "webextension-polyfill": "^0.4.0",
     "webpack": "4.16.3",
     "webpack-bugsnag-plugins": "^1.3.0",
     "webpack-cli": "3.1.0",

src/chrome-manifest.json

@@ -43,7 +43,8 @@
     "contextMenus",
     "notifications",
     "idle",
-    "tabs"
+    "tabs",
+    "storage"
   ],
   "optional_permissions": ["*://*/"],
   "externally_connectable": {

src/firefox-manifest.json

@@ -41,7 +41,8 @@
     "contextMenus",
     "notifications",
     "idle",
-    "tabs"
+    "tabs",
+    "storage"
   ],
   "optional_permissions": [
     "*://*/"