Fixes for web_accessible_resources sample. (GoogleChrome#946)

* Fixes for web_accessible_resources sample.

* Address feedback.

api-samples/web-accessible-resources/README.md

@@ -0,0 +1,14 @@
+# Web Accessible Resources
+
+This sample demonstrates using the [web_accessible_resources](https://developer.chrome.com/docs/extensions/mv3/manifest/web_accessible_resources/)
+key in the manifest.json file to control access to assets within an extension.
+
+## Overview
+
+This sample shows how image assets within an extension can be exposed to pages on the web.
+
+## Running this extension
+
+1. Clone this repository.
+2. Load this directory in Chrome as an [unpacked extension](https://developer.chrome.com/docs/extensions/mv3/getstarted/development-basics/#load-unpacked).
+3. Follow the instructions on the newly opened tab.

api-samples/web-accessible-resources/readme.html → api-samples/web-accessible-resources/index.html

@@ -4,7 +4,7 @@
     <meta charset="UTF-8" />
     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
-    <title>Web Accessible Resources - Readme</title>
+    <title>Web Accessible Resources</title>
     <style>
       body {
         font-family: Helvetica, Arial, sans-serif;
@@ -35,7 +35,7 @@ <h1>Web Accessible Resources Demo</h1>
       do this, we define a set of
       <a
         href="https://developer.chrome.com/docs/extensions/mv3/manifest/web_accessible_resources/"
-        ><code>"web_accessable_resources"</code></a
+        ><code>"web_accessible_resources"</code></a
       >
       in our <a href="manifest.json">manifest.json</a>. This object specifies
       what assets should be accessible to which external resources.

api-samples/web-accessible-resources/manifest.json

@@ -3,7 +3,7 @@
   "version": "1.0",
   "manifest_version": 3,
   "background": {
-    "service_worker": "background.js"
+    "service_worker": "service-worker.js"
   },
   "action": {},
   "content_scripts": [

api-samples/web-accessible-resources/background.js → api-samples/web-accessible-resources/service-worker.js

@@ -9,6 +9,5 @@ chrome.action.onClicked.addListener(() => {
 });
 
 function showReadme() {
-  const url = chrome.runtime.getURL('readme.html');
-  chrome.tabs.create({ url });
+  chrome.tabs.create({ url: '/index.html' });
 }