Adding `content_security_policy` to a few sample extensions

chrome/common/extensions/docs/examples/api/tabs/screenshot/screenshot.js

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// To make sure we can uniquely identify each screenshot tab, add an id as a
-// query param to the url that displays the screenshot.
-var id = 100;
-
-function takeScreenshot() {
-  chrome.tabs.captureVisibleTab(null, function(img) {
-    var screenshotUrl = img;
-    var viewTabUrl = [chrome.extension.getURL('screenshot.html'),
-                      '?id=', id++].join('');
-
-    chrome.tabs.create({url: viewTabUrl}, function(tab) {
-      var targetId = tab.id;
-
-      var addSnapshotImageToTab = function(tabId, changedProps) {
-        // We are waiting for the tab we opened to finish loading.
-        // Check that the the tab's id matches the tab we opened,
-        // and that the tab is done loading.
-        if (tabId != targetId || changedProps.status != "complete")
-          return;
-
-        // Passing the above test means this is the event we were waiting for.
-        // There is nothing we need to do for future onUpdated events, so we
-        // use removeListner to stop geting called when onUpdated events fire.
-        chrome.tabs.onUpdated.removeListener(addSnapshotImageToTab);
-
-        // Look through all views to find the window which will display
-        // the screenshot.  The url of the tab which will display the
-        // screenshot includes a query parameter with a unique id, which
-        // ensures that exactly one view will have the matching URL.
-        var views = chrome.extension.getViews();
-        for (var i = 0; i < views.length; i++) {
-          var view = views[i];
-          if (view.location.href == viewTabUrl) {
-            view.setScreenshotUrl(screenshotUrl);
-            break;
-          }
-        }
-      };
-      chrome.tabs.onUpdated.addListener(addSnapshotImageToTab);
-
-    });
-  });
+function setScreenshotUrl(url) {
+  document.getElementById('target').src = url;
 }
-
-// Listen for a click on the camera icon.  On that click, take a screenshot.
-chrome.browserAction.onClicked.addListener(function(tab) {
-  if (tab.url.match(/code.google.com/)) {
-    takeScreenshot();
-  } else {
-    alert('This sample can only take screenshots of code.google.com pages');
-  }
-});