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chrome/common/extensions/docs/server2/templates/articles/app_external.html

+<h1>Embed Content</h1>
+
+
+<p>
+The <a href="app_architecture.html#security">packaged apps security model</a> disallows
+external content in iframes and
+the use of inline scripting and <code>eval()</code>.
+You can override these restrictions,
+but your external content must be isolated from the app.
+</p>
+
+<p>
+Isolated content cannot directly
+access the app's data or any of the APIs.
+Use cross-origin XMLHttpRequests
+and post-messaging to communicate between the event page and sandboxed content
+and indirectly access the APIs.
+</p>
+
+<p class="note">
+<b>API Samples: </b>
+Want to play with the code?
+Check out the
+<a href="https://github.com/GoogleChrome/chrome-app-samples/tree/master/eval-in-iframe">eval-in-iframe</a>
+and <a href="https://github.com/GoogleChrome/chrome-app-samples/tree/master/regex-tester">regex-tester</a> samples.
+</p>
+
+<h2 id="external">Referencing external resources</h2>
+
+<p>
+The <a href="app_csp.html">Content Security Policy</a> used by apps disallows
+the use of many kinds of remote URLs, so you can't directly reference external
+images, stylesheets, or fonts from an app page. Instead, you can use use
+cross-origin XMLHttpRequests to fetch these resources,
+and then serve them via <code>blob:</code> URLs.
+</p>
+
+<h3>Manifest requirement</h3>
+
+<p>
+To be able to do cross-origin XMLHttpRequests, you'll need to add a permission
+for the remote URL's host:
+</p>
+
+<pre>
+"permissions": [
+    "...",
+    "https://supersweetdomainbutnotcspfriendly.com/"
+  ]
+</pre>
+
+<h3>Cross-origin XMLHttpRequest</h3>
+
+<p>
+Fetch the remote URL into the app and serve its contents as a <code>blob:</code>
+URL:
+</p>
+
+<pre>
+var xhr = new XMLHttpRequest();
+xhr.open('GET', 'https://supersweetdomainbutnotcspfriendly.com/image.png', true);
+xhr.responseType = 'blob';
+xhr.onload = function(e) {
+  var img = document.createElement('img');
+  img.src = window.webkitURL.createObjectURL(this.response);
+  document.body.appendChild(img);
+};
+
+xhr.send();
+</pre>
+
+<p>You may want to <a href="offline_apps.html#saving-locally">save</a>
+these resources locally, so that they are available offline.</p>
+
+<h2 id="browsertag">Embed external web pages</h2>
+
+<p class="note">
+<b>API Sample: </b>
+Want to play with the code? Check out the
+<a href="https://github.com/GoogleChrome/chrome-app-samples/tree/master/browser-tag">browser-tag</a>
+sample.
+</p>
+
+<p>
+The <code>browser</code> tag allows you to embed external web content in your
+app, for example, a web page. It replaces iframes that point to remote URLs,
+which are disabled inside packaged apps. Unlike iframes, the
+<code>browser</code> tag runs in a separate process. This means that an exploit
+inside of it will still be isolated and won't be able to gain elevated
+privileges. Further, since its storage (cookies, etc.) is isolated from the app,
+there is no way for the web content to access any of the app's data.
+</p>
+
+<h3>Add browser element</h3>
+
+<p>
+Your <code>browser</code> element must include the URL to the source content
+and specify its dimensions.
+</p>
+
+<pre>&lt;browser src="http://news.google.com/" width="640" height="480">&lt;/browser></pre>
+
+<h3>Update properties</h3>
+
+<p>
+To dynamically change the <code>src</code>, <code>width</code> and
+<code>height</code> properties of a <code>browser</code> tag, you can either
+set those properties directly on the JavaScript object, or use the
+<code>setAttribute</code> DOM function.
+</p>
+
+<pre>
+document.querySelector('#mybrowser').src =
+    'http://blog.chromium.org/';
+// or
+document.querySelector('#mybrowser').setAttribute(
+    'src', 'http://blog.chromium.org/');
+</pre>
+
+<h2 id="sandboxing">Sandbox local content</h2>
+
+<p>
+Sandboxing allows specified pages
+to be served in a sandboxed, unique origin.
+These pages are then exempt from their Content Security Policy.
+Sandboxed pages can use iframes, inline scripting,
+and <code>eval()</code>.
+Check out the manifest field description for
+<a href="manifest.html#sandbox">sandbox</a>.
+</p>
+
+<p>
+It's a trade-off though:
+sandboxed pages can't use the chrome.* APIs.
+If you need to do things like <code>eval()</code>,
+go this route to be exempt from CSP,
+but you won't be able to use the cool new stuff.
+</p>
+
+<h3>Use inline scripts in sandbox</h3>
+
+<p>
+Here's a sample sandboxed page
+which uses an inline script and <code>eval()</code>:
+</p>
+
+<pre>
+&lt;html>
+  &lt;body>
+    &lt;h1>Woot&lt;/h1>
+    &lt;script>
+      document.write('I am an inline script.&lt;br>');
+      eval('document.write(\'I am an eval-ed inline script.\');');
+    &lt;/script>
+  &lt;/body>
+&lt;/html>
+</pre>
+
+<h3>Include sandbox in manifest</h3>
+
+<p>
+You need to include the <code>sandbox</code> field in the manifest
+and list the app pages to be served in a sandbox:
+</p>
+
+<pre>
+"sandbox": {
+  "pages": ["sandboxed.html"]
+}
+</pre>
+
+<h3>Opening a sandboxed page in a window</h3>
+
+<p>
+Just like any other app pages,
+you can create a window that the sandboxed page opens in.
+Here's a sample that creates two windows,
+one for the main app window that isn't sandboxed,
+and one for the sandboxed page:
+</p>
+
+<pre>
+chrome.experimental.app.onLaunched.addListener(function() {
+  chrome.app.window.create('window.html', {
+    'width': 400,
+    'height': 400,
+    'left': 0,
+    'top': 0
+  });
+
+  chrome.app.window.create('sandboxed.html', {
+    'width': 400,
+    'height': 400,
+    'left': 400,
+    'top': 0
+  });
+});
+</pre>
+
+<h3>Embedding a sandboxed page in an app page</h3>
+
+<p>Sandboxed pages can also be embedded within another app page
+  using an <code>iframe</code>:</p>
+
+<pre>
+&lt;!DOCTYPE html>
+&lt;html>
+&lt;head>
+&lt;/head>
+  &lt;body>
+    &lt;p>I am normal app window.&lt;/p>
+
+    &lt;iframe src="sandboxed.html" width="300" height="200">&lt;/iframe>
+  &lt;/body>
+&lt;/html>
+</pre>
+
+
+<h2 id="postMessage">Sending messages to sandboxed pages</h2>
+
+<p>
+There are two parts to sending a message:
+you need to post a message from the sender page/window,
+and listen for messages on the receiving page/window.
+</p>
+
+<h3>Post message</h3>
+
+<p>
+You can use <code>postMessage</code> to communicate
+between your app and sandboxed content.
+Here's a sample background script
+that posts a message to the sandboxed page it
+opens:
+</p>
+
+<pre>
+var myWin = null;
+
+chrome.experimental.app.onLaunched.addListener(function() {
+  chrome.app.window.create('sandboxed.html', {
+    'width': 400,
+    'height': 400
+  }, function(win) {
+       myWin = win;
+       myWin.postMessage('Just wanted to say hey.', '*');
+     });
+});
+</pre>
+
+<p>
+Generally speaking on the web,
+you want to specify the exact origin
+from where the message is sent.
+Packaged apps have no access
+to the unique origin of sandboxed content,
+so you can only whitelist all origins
+as acceptable origins ('*').
+On the receiving end,
+you generally want to check the origin;
+but since packaged apps content is contained,
+it isn't necessary.
+To find out more,
+see <a href="https://developer.mozilla.org/en/DOM/window.postMessage">window.postMessage</a>.
+</p>
+
+<h3>Listen for message</h3>
+
+<p>
+Here's a sample message receiver
+that gets added to your sandboxed page:
+</p>
+
+<pre>
+var messageHandler = function(e) {
+  console.log('Background script says hello.', e.data);
+};
+
+window.addEventListener('message', messageHandler);
+</pre>
+
+<p class="backtotop"><a href="#top">Back to top</a></p>