Add icon

extension/icon.svg

@@ -0,0 +1,12 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1" viewBox="0 0 20 20">
+  <defs>
+    <clipPath id="b">
+      <use width="100%" height="100%" xlink:href="#a"/>
+    </clipPath>
+  </defs>
+  <g color="#000" transform="translate(-12 -11)">
+    <rect style="marker:none" width="17" height="4" x="13" y="25" fill="#585858" clip-path="url(#b)" overflow="visible" ry="0" transform="matrix(1.00048 0 0 1.3584 0 -10)"/>
+    <rect style="marker:none" width="17" height="4" x="13" y="12" fill="#585858" clip-path="url(#b)" overflow="visible" ry="0" transform="matrix(.99987 0 0 1.57087 0 -7)"/>
+    <rect style="marker:none" id="a" width="18" height="18" x="13" y="12" fill="none" stroke="#999" stroke-width="2" overflow="visible" ry="3"/>
+  </g>
+</svg>

extension/manifest.json

@@ -4,7 +4,8 @@
     "version": "1.0.0",
     "page_action": {
       "browser_style": true,
-      "default_title": "Ban banners"
+      "default_title": "Ban banners",
+      "default_icon": "/icon.svg"
     },
     "background": {
         "scripts": ["background_script.js"]