[Extension Docs]Print Sample Extension: replace tabs.update with tabs.executeScript

Attempting to use the print this page extension results in Unchecked runtime.lastError: JavaScript URLs are not allowed in chrome.tabs.update. Use chrome.tabs.executeScript instead.

https://developer.chrome.com/extensions/samples needs to be updated as well.

Change-Id: Iea56f32cae87dc4286fe5e1cd61cb5e4ada1e478
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1554794Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Kyle Spiers <ksspiers@google.com>
Cr-Commit-Position: refs/heads/master@{#657382}

chrome/common/extensions/docs/examples/api/browserAction/print/background.js

@@ -4,6 +4,7 @@
 
 // Called when the user clicks on the browser action.
 chrome.browserAction.onClicked.addListener(function(tab) {
-  var action_url = "javascript:window.print();";
-  chrome.tabs.update(tab.id, {url: action_url});
+  chrome.tabs.executeScript(
+    tab.id,
+    {code: 'window.print();'});
 });