New icon, kudos to @lewisacidic

src/background.js

@@ -728,7 +728,7 @@ function onExtensionInstalled(details) {
         chrome.notifications.create(id, {
             title: title,
             message: message,
-            iconUrl: "icon-lock.png",
+            iconUrl: "icon.png",
             type: "basic"
         });
     };

src/icon-lock.svg

@@ -1 +0,0 @@
-<?xml version="1.0" ?><!DOCTYPE svg  PUBLIC '-//W3C//DTD SVG 1.1//EN'  'http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd'><svg enable-background="new 0 0 164 164" height="164px" id="Layer_1" version="1.1" viewBox="0 0 164 164" width="164px" xml:space="preserve" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><path clip-rule="evenodd" d="M26.644,64.78h110.394c6.875,0,12.5,5.625,12.5,12.5v74.22  c0,6.875-5.625,12.5-12.5,12.5H26.644c-6.875,0-12.5-5.625-12.5-12.5V77.28C14.144,70.405,19.769,64.78,26.644,64.78L26.644,64.78z   M88.147,116.323c7.847-4.176,11.097-9.207,11.447-13.136c1.881-20.996-36.054-21.461-35.534,0.013  c0.093,3.852,2.966,8.658,10.142,13.104c-2.026,9.464-3.1,15.26-3.1,25.063c6.798,0,13.597,0,20.395,0  C91.497,131.564,90.174,125.786,88.147,116.323L88.147,116.323z M105.354,55.803c0.24-44.592-47.027-44.378-47.027,0.782  c-7.837,0-15.675,0-23.513,0c0-74.752,94.054-75.025,94.054-0.782C121.029,55.803,128.867,55.803,105.354,55.803z" fill="#5f8dd3" fill-rule="evenodd"/></svg>

src/icon.svg

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg xmlns="http://www.w3.org/2000/svg" width="128" height="128" viewBox="0 0 12.7 12.7" version="1.1">
+  <g transform="translate(0,-284.29998)">
+    <path d="m 2.4292406,284.32258 -0.00426,5.194 0.6179814,0.66441 -0.6190211,0.57483 0.6179814,0.6644 -0.6203892,0.61935 0.6193496,0.61989 -0.6198695,0.61986 0.6193496,0.61986 -0.6203903,0.61988 -0.00104,1.23922 1.23922,1.24077 0.95706,10e-4 0.6203902,-0.61988 0.00156,-2.19346 h 0.00312 v -3.01723 h 1.2901822 c 2.1984804,0 4.0624321,-1.08312 4.0624321,-3.52057 0,-2.5171 -1.8482601,-3.34585 -4.1263952,-3.34585 -1.6468851,-0.006 -2.390624,-0.004 -4.0373053,0.0194 z m 2.8110727,1.84482 h 1.0832115 c 1.2744817,0 1.9750539,0.39825 1.9750539,1.48155 0,1.08331 -0.6211981,1.65682 -1.9116106,1.65682 H 5.2403133 Z m -1.2428599,2.97944 0.6198694,-0.68973 -0.00104,7.30324 -0.6203893,0.61934 z" fill="#5f8dd3" />
+  </g>
+</svg>

src/manifest-chromium.json

@@ -11,10 +11,10 @@
         "scripts": ["js/background.dist.js"]
     },
     "icons": {
-        "128": "icon-lock.png"
+        "128": "icon.png"
     },
     "browser_action": {
-        "default_icon": "icon-lock.png",
+        "default_icon": "icon.png",
         "default_popup": "popup/popup.html"
     },
     "options_ui": {

src/manifest-firefox.json

@@ -10,10 +10,10 @@
         "scripts": ["js/background.dist.js"]
     },
     "icons": {
-        "128": "icon-lock.png"
+        "128": "icon.png"
     },
     "browser_action": {
-        "default_icon": "icon-lock.png",
+        "default_icon": "icon.png",
         "default_popup": "popup/popup.html"
     },
     "options_ui": {