RSS Extension: Build script, closure, hardening.

- Sandbox the iframe and sanitize the input used.
- Remove special 'synchronous' testing flag (not needed).
  - Multi-line quote requirement also no longer needed.
- Change default reader list
  - (replace deprecated Bloglines service with Newsblur).
- Deflake and re-enable the RSS extension tests.
- Up the version by two (from 2.2.3 to 2.2.5, since 2.2.4
  is live already).

Bug: 340354, b/137075999
Change-Id: I6eac37fae9e2228aeabe68ccf1fd34b9b36ac6ba
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2264059
Commit-Queue: Finnur Thorarinsson <finnur@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#785861}

chrome/browser/extensions/subscribe_page_action_browsertest.cc

@@ -74,7 +74,7 @@ GURL GetFeedUrl(net::EmbeddedTestServer* server,
     // sniffing won't work, in other words, as is the case for malformed feeds.
     return GURL(std::string(kExtensionScheme) + url::kStandardSchemeSeparator +
                 extension_id + std::string(kSubscribePage) + std::string("?") +
-                feed_url.spec() + std::string("&synchronous"));
+                feed_url.spec());
   } else {
     // Navigate to the feed content (which will cause the extension to try to
     // sniff the type and display the subscribe page in another tab.
@@ -82,6 +82,37 @@ GURL GetFeedUrl(net::EmbeddedTestServer* server,
   }
 }
 
+class NamedFrameCreatedObserver : public content::WebContentsObserver {
+ public:
+  NamedFrameCreatedObserver(WebContents* web_contents,
+                            const std::string& frame_name)
+      : WebContentsObserver(web_contents), frame_name_(frame_name) {}
+
+  content::RenderFrameHost* Wait() {
+    if (!frame_) {
+      run_loop_.Run();
+    }
+
+    return frame_;
+  }
+
+ private:
+  void RenderFrameCreated(
+      content::RenderFrameHost* render_frame_host) override {
+    if (render_frame_host->GetFrameName() != frame_name_)
+      return;
+
+    frame_ = render_frame_host;
+    run_loop_.Quit();
+  }
+
+  base::RunLoop run_loop_;
+  content::RenderFrameHost* frame_ = nullptr;
+  std::string frame_name_;
+
+  DISALLOW_COPY_AND_ASSIGN(NamedFrameCreatedObserver);
+};
+
 bool ValidatePageElement(content::RenderFrameHost* frame,
                          const std::string& javascript,
                          const std::string& expected_value) {
@@ -108,18 +139,29 @@ void NavigateToFeedAndValidate(net::EmbeddedTestServer* server,
                                const std::string& expected_feed_title,
                                const std::string& expected_item_title,
                                const std::string& expected_item_desc,
-                               const std::string& expected_error) {
+                               const std::string& expected_error,
+                               std::string expected_msg) {
   if (sniff_xml_type) {
     // TODO(finnur): Implement this is a non-flaky way.
   }
 
+  content::DOMMessageQueue message_queue;
+
+  WebContents* tab = browser->tab_strip_model()->GetActiveWebContents();
+  NamedFrameCreatedObserver subframe_observer(tab, "preview");
+
   // Navigate to the subscribe page directly.
   ui_test_utils::NavigateToURL(browser,
                                GetFeedUrl(server, url, true, extension_id));
+  ASSERT_TRUE(subframe_observer.Wait() != nullptr);
+
+  std::string message;
+  ASSERT_TRUE(message_queue.WaitForMessage(&message));
+  expected_msg = "\"" + expected_msg + "\"";
+  EXPECT_STREQ(expected_msg.c_str(), message.c_str());
 
-  WebContents* tab = browser->tab_strip_model()->GetActiveWebContents();
   content::RenderFrameHost* frame = content::FrameMatchingPredicate(
-      tab, base::Bind(&content::FrameIsChildOfMainFrame));
+      tab, base::Bind(&content::FrameMatchesName, "preview"));
   ASSERT_TRUE(ValidatePageElement(
       tab->GetMainFrame(), kScriptFeedTitle, expected_feed_title));
   ASSERT_TRUE(ValidatePageElement(frame, kScriptAnchor, expected_item_title));
@@ -146,8 +188,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSMultiRelLink) {
   ASSERT_TRUE(WaitForPageActionVisibilityChangeTo(1));
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed1) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeed1) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -157,11 +198,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed1) {
 
   NavigateToFeedAndValidate(embedded_test_server(), kValidFeed1, browser(), id,
                             true, "Feed for MyFeedTitle", "Title 1", "Desc",
-                            "No error");
+                            "No error", "PreviewReady");
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed2) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeed2) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -171,11 +211,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed2) {
 
   NavigateToFeedAndValidate(embedded_test_server(), kValidFeed2, browser(), id,
                             true, "Feed for MyFeed2", "My item title1",
-                            "This is a summary.", "No error");
+                            "This is a summary.", "No error", "PreviewReady");
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed3) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeed3) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -185,11 +224,11 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed3) {
 
   NavigateToFeedAndValidate(embedded_test_server(), kValidFeed3, browser(), id,
                             true, "Feed for Google Code buglist rss feed",
-                            "My dear title", "My dear content", "No error");
+                            "My dear title", "My dear content", "No error",
+                            "PreviewReady");
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed4) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeed4) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -200,11 +239,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed4) {
   NavigateToFeedAndValidate(embedded_test_server(), kValidFeed4, browser(), id,
                             true, "Feed for Title chars <script> %23 stop",
                             "Title chars  %23 stop", "My dear content %23 stop",
-                            "No error");
+                            "No error", "PreviewReady");
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed0) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeed0) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -216,11 +254,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed0) {
   // trigger a NOTREACHED).
   NavigateToFeedAndValidate(embedded_test_server(), kValidFeed0, browser(), id,
                             true, "Feed for MyFeedTitle", "Title 1",
-                            "Desc VIDEO", "No error");
+                            "Desc VIDEO", "No error", "PreviewReady");
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed5) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeed5) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -232,11 +269,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed5) {
   NavigateToFeedAndValidate(
       embedded_test_server(), kValidFeed5, browser(), id, true,
       "Feed for Unknown feed name", "element 'anchor_0' not found",
-      "element 'desc_0' not found", "This feed contains no entries.");
+      "element 'desc_0' not found", "This feed contains no entries.", "Error");
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed6) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeed6) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -247,9 +283,14 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, DISABLED_RSSParseFeedValidFeed6) {
   // Feed that is technically invalid but still parseable.
   NavigateToFeedAndValidate(embedded_test_server(), kValidFeed6, browser(), id,
                             true, "Feed for MyFeedTitle", "Title 1", "Desc",
-                            "No error");
+                            "No error", "PreviewReady");
 }
 
+// TODO(finnur): Once we're able to Closure-compile (via the Chrome build
+//               process) the extension along with the HTML sanitizer, we should
+//               add a test to confirm <img src="foo.jpg" alt="foo" /> is
+//               preserved after sanitizing (the xkcd test).
+
 IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed1) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
@@ -262,7 +303,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed1) {
   NavigateToFeedAndValidate(
       embedded_test_server(), kInvalidFeed1, browser(), id, false,
       "Feed for Unknown feed name", "element 'anchor_0' not found",
-      "element 'desc_0' not found", "This feed contains no entries.");
+      "element 'desc_0' not found", "This feed contains no entries.", "Error");
 }
 
 IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed2) {
@@ -277,7 +318,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed2) {
   NavigateToFeedAndValidate(
       embedded_test_server(), kInvalidFeed2, browser(), id, false,
       "Feed for Unknown feed name", "element 'anchor_0' not found",
-      "element 'desc_0' not found", "This feed contains no entries.");
+      "element 'desc_0' not found", "This feed contains no entries.", "Error");
 }
 
 IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed3) {
@@ -292,7 +333,7 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed3) {
   NavigateToFeedAndValidate(
       embedded_test_server(), "/foo.xml", browser(), id, false,
       "Feed for Unknown feed name", "element 'anchor_0' not found",
-      "element 'desc_0' not found", "This feed contains no entries.");
+      "element 'desc_0' not found", "This feed contains no entries.", "Error");
 }
 
 IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed4) {
@@ -313,12 +354,10 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedInvalidFeed4) {
   NavigateToFeedAndValidate(
       embedded_test_server(), kFeedTripleEncoded, browser(), id, true,
       "Feed for Unknown feed name", "element 'anchor_0' not found",
-      "element 'desc_0' not found", "This feed contains no entries.");
+      "element 'desc_0' not found", "This feed contains no entries.", "Error");
 }
 
-// This test is flaky on all platforms; see http://crbug.com/340354
-IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest,
-                       DISABLED_RSSParseFeedValidFeedNoLinks) {
+IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest, RSSParseFeedValidFeedNoLinks) {
   ASSERT_TRUE(embedded_test_server()->Start());
 
   const Extension* extension = LoadExtension(
@@ -329,7 +368,8 @@ IN_PROC_BROWSER_TEST_F(ExtensionBrowserTest,
   // Valid feed but containing no links.
   NavigateToFeedAndValidate(embedded_test_server(), kValidFeedNoLinks,
                             browser(), id, true, "Feed for MyFeedTitle",
-                            "Title with no link", "Desc", "No error");
+                            "Title with no link", "Desc", "No error",
+                            "PreviewReady");
 }
 
 }  // namespace extensions

chrome/test/data/extensions/subscribe_page_action/build.sh

+#!/bin/bash
+# Copyright 2020 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.
+
+closure_path=../../../../../third_party/google-closure-library
+compiler_jar=compiler/closure-compiler-v20200614.jar
+
+echo
+echo '-------------------------------------------'
+echo 'Building the RSS extension.'
+echo '-------------------------------------------'
+
+echo
+echo 'Recreating out/ from scratch...'
+rm -rf out/
+mkdir out/
+
+echo 'Copying manifest.json' && cp -r src/manifest.json out/
+echo Copying _locales      && cp -r src/_locales out/_locales
+echo Copying .html         && cp src/*.html out/
+echo Copying .css          && cp src/*.css out/
+echo Copying .png          && cp src/*.png out/
+
+echo 'Copying javascipt files (all except iframe.js, which will be compiled).'
+echo 'Copying background.js'   && cp src/background.js out/background.js
+echo 'Copying common.js'       && cp src/common.js out/common.js
+echo 'Copying doc_start.js'    && cp src/doc_start.js out/doc_start.js
+echo 'Copying feed_finder.js'  && cp src/feed_finder.js out/feed_finder.js
+echo 'Copying options.js'      && cp src/options.js out/options.js
+echo 'Copying popup.js'        && cp src/popup.js out/popup.js
+echo 'Copying sniff_common.js' && cp src/sniff_common.js out/sniff_common.js
+echo 'Copying subscribe.js'    && cp src/subscribe.js out/subscribe.js
+# NOTE: test_*.js files should not be copied over.
+echo
+
+# Uncomment to see hashes for scripts.
+# echo 'SHA hashes:'
+# echo 'subscribe.js       sha256-'$(cat src/subscribe.js | openssl dgst -sha256 -binary | openssl enc -base64)
+# echo 'freeflow foo       sha256-'$(echo -n "console.log('foo');" | openssl dgst -sha256 -binary | openssl enc -base64)
+# echo
+
+echo 'Closure compiling:'
+echo 'Using' $compiler_jar
+echo '      ^ Make sure this is present and up to date.'
+
+echo 'Compiling iframe.js.'
+$closure_path/closure/bin/build/closurebuilder.py \
+  --root=src/ \
+  --root=$closure_path \
+  --namespace="RSSExtension.IFrame" \
+  --output_mode=compiled \
+  --compiler_jar=$compiler_jar \
+  > out/iframe.js
+
+echo 'The contents of out/ now contain the extension to be uploaded.'
+echo
+
+echo 'Extension:'
+grep "\"version\"" out/manifest.json
+echo '              ^ Please make sure this version is correct!!'
+

chrome/test/data/extensions/subscribe_page_action/src/common.js

@@ -11,8 +11,8 @@ var storageEnabled = window.localStorage != null;
 function defaultReaderList() {
   // This is the default list, unless replaced by what was saved previously.
   return [
-    { 'url': 'http://www.bloglines.com/login?r=/sub/%s',
-      'description': 'Bloglines'
+    { 'url': 'http://www.newsblur.com/?url=%s',
+      'description': 'Newsblur'
     },
     { 'url': 'http://add.my.yahoo.com/rss?url=%s',
       'description': 'My Yahoo'

chrome/test/data/extensions/subscribe_page_action/src/iframe.js

-/* Copyright (c) 2009 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.
-*/
-
-/* Use only multi-line comments in this file, since during testing
-   its contents will get read from disk and stuffed into the
-   iframe .src tag, which is a process that doesn't preserve line
-   breaks and makes single-line comments comment out the rest of the code.
-*/
-
-/* The maximum number of feed items to show in the preview. */
+// Copyright (c) 2009 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.
+
+goog.provide('RSSExtension.IFrame');
+
+goog.require('goog.html.sanitizer.HtmlSanitizer');
+goog.require('goog.dom.safe');
+
+// The maximum number of feed items to show in the preview.
 var maxFeedItems = 10;
 
-/* The maximum number of characters to show in the feed item title. */
+// The maximum number of characters to show in the feed item title.
 var maxTitleCount = 1024;
 
-/* Find the token and target origin for this conversation from the HTML. The
-   token is used for secure communication, and is generated and stuffed into the
-   frame by subscribe.js.
-*/
+// Find the token and target origin for this conversation from the HTML. The
+// token is used for secure communication, and is generated and stuffed into the
+// frame by subscribe.js.
 var token = '';
 var targetOrigin = '';
 var html = document.documentElement.outerHTML;
@@ -45,20 +42,20 @@ if (token.length > 0) {
     if (doc) {
       buildPreview(doc);
     } else {
-      /* Already handled in subscribe.html */
+      // Already handled in subscribe.html.
     }
   }
 }
 
 function buildPreview(doc) {
-  /* Start building the part we render inside an IFRAME. We use a table to
-     ensure that items are separated vertically from each other. */
+  // Start building the part we render inside an IFRAME. We use a table to
+  // ensure that items are separated vertically from each other.
   var table = document.createElement("table");
   var tbody = document.createElement("tbody");
   table.appendChild(tbody);
 
-  /* Now parse the rest. Some use <entry> for each feed item, others use
-     <channel><item>. */
+  // Now parse the rest. Some use <entry> for each feed item, others use
+  // <channel><item>.
   var entries = doc.getElementsByTagName('entry');
   if (entries.length == 0)
     entries = doc.getElementsByTagName('item');
@@ -66,19 +63,19 @@ function buildPreview(doc) {
   for (i = 0; i < entries.length && i < maxFeedItems; ++i) {
     item = entries.item(i);
 
-    /* Grab the title for the feed item. */
+    // Grab the title for the feed item.
     var itemTitle = item.getElementsByTagName('title')[0];
     if (itemTitle)
       itemTitle = itemTitle.textContent;
     else
       itemTitle = "Unknown title";
 
-    /* Ensure max length for title. */
+    // Ensure max length for title.
     if (itemTitle.length > maxTitleCount)
       itemTitle = itemTitle.substring(0, maxTitleCount) + "...";
 
-    /* Grab the description.
-       TODO(aa): Do we need to check for type=html here? */
+    // Grab the description.
+    // TODO(aa): Do we need to check for type=html here?
     var itemDesc = item.getElementsByTagName('description')[0];
     if (!itemDesc)
       itemDesc = item.getElementsByTagName('summary')[0];
@@ -90,7 +87,7 @@ function buildPreview(doc) {
     else
       itemDesc = "";
 
-    /* Grab the link URL. */
+    // Grab the link URL.
     var itemLink = item.getElementsByTagName('link');
     var link = "";
     if (itemLink.length > 0) {
@@ -104,21 +101,28 @@ function buildPreview(doc) {
     var tr = document.createElement("tr");
     var td = document.createElement("td");
 
-    /* If we found a link we'll create an anchor element,
-    otherwise just use a bold headline for the title. */
+    var sanitizer = window.domAutomationController === undefined ?
+        new goog.html.sanitizer.HtmlSanitizer.Builder()
+            .withCustomNetworkRequestUrlPolicy(goog.html.SafeUrl.sanitize)
+            .withCustomUrlPolicy(goog.html.SafeUrl.sanitize)
+            .build()
+        : goog.html.sanitizer.HtmlSanitizer;
+
+    // If we found a link we'll create an anchor element,
+    // otherwise just use a bold headline for the title.
     var anchor = (link != "") ? document.createElement("a") :
                                 document.createElement("strong");
     anchor.id = "anchor_" + String(i);
     if (link != "")
-      anchor.href = link;
-    anchor.innerHTML = itemTitle;
+      goog.dom.safe.setAnchorHref(anchor, goog.html.SafeUrl.sanitize(link));
+    goog.dom.safe.setInnerHtml(anchor, sanitizer.sanitize(itemTitle));
     anchor.target = "_top";
     anchor.className = "item_title";
 
     var span = document.createElement("span");
     span.id = "desc_" + String(i);
     span.className = "item_desc";
-    span.innerHTML = itemDesc;
+    goog.dom.safe.setInnerHtml(span, sanitizer.sanitize(itemDesc));
 
     td.appendChild(anchor);
     td.appendChild(document.createElement("br"));
@@ -132,4 +136,8 @@ function buildPreview(doc) {
 
   table.appendChild(tbody);
   document.body.appendChild(table);
+
+  if (window.domAutomationController) {
+    window.domAutomationController.send('PreviewReady');
+  }
 }

chrome/test/data/extensions/subscribe_page_action/src/manifest.json

@@ -25,6 +25,6 @@
     "default_title": "__MSG_rss_subscription_default_title__"
   },
   "permissions": [ "tabs", "http://*/*", "https://*/*", "storage" ],
-  "version": "2.2.3",
+  "version": "2.2.5",
   "web_accessible_resources": [ "iframe.js", "style.css" ]
 }

chrome/test/data/extensions/subscribe_page_action/src/subscribe.js

@@ -12,14 +12,6 @@ var feedUrl = decodeURIComponent(queryString[0]);
 // This extension's ID.
 var extension_id = chrome.i18n.getMessage("@@extension_id");
 
-// During testing, we cannot load the iframe and stylesheet from an external
-// source, so we allow loading them synchronously and stuff the frame with the
-// results. Since this is only allowed during testing, it isn't supported for
-// the official extension ID.
-var synchronousRequest =
-    extension_id != "nlbjncdgjeocebhnmkbbbdekmmmcbfjd" ?
-        queryString[1] == "synchronous" : false;
-
 // The XMLHttpRequest object that tries to load and parse the feed, and (if
 // testing) also the style sheet and the frame js.
 var req;
@@ -96,38 +88,19 @@ function main() {
   crypto.getRandomValues(tokenArray);
   token = [].join.call(tokenArray);
 
-  // Now fetch the data.
-  req = new XMLHttpRequest();
-  if (synchronousRequest) {
-    // Tests that load the html page directly through a file:// url don't have
-    // access to the js and css from the frame so we must load them first and
-    // inject them into the src for the iframe.
-    req.open("GET", "style.css", false);
-    req.send(null);
-
-    styleSheet = "<style>" + req.responseText + "</style>";
-
-    req.open("GET", "iframe.js", false);
-    req.send(null);
-
-    if (req.responseText.indexOf('//') != -1) {
-      console.log('Error: Single-line comment(s) found in iframe.js');
-    } else {
-      frameScript = "<script>" +
-                    req.responseText +
-                    "<" + "/script>";
-    }
-  } else {
-    // Normal loading just requires links to the css and the js file.
   styleSheet = "<link rel='stylesheet' type='text/css' href='" +
                    chrome.extension.getURL("style.css") + "'>";
-    frameScript = "<script src='" + chrome.extension.getURL("iframe.js") +
+  frameScript = window.domAutomationController !== undefined ? "<script src='" +
+                    chrome.extension.getURL("test_support.js") +
+                    "'></" + "script>" : "";
+  frameScript += "<script src='" + chrome.extension.getURL("iframe.js") +
                      "'></" + "script>";
-  }
 
+  // Now fetch the feed data.
+  req = new XMLHttpRequest();
   req.onload = handleResponse;
   req.onerror = handleError;
-  req.open("GET", feedUrl, !synchronousRequest);
+  req.open("GET", feedUrl, true);
   // Not everyone sets the mime type correctly, which causes handleResponse
   // to fail to XML parse the response text from the server. By forcing
   // it to text/xml we avoid this.
@@ -157,6 +130,10 @@ function handleFeedParsingFailed(error) {
   // The tests always expect an IFRAME, so add one showing the error.
   var html = "<body><span id=\"error\" class=\"item_desc\">" + error +
                "</span></body>";
+  if (window.domAutomationController) {
+    html += "<script src='" + chrome.extension.getURL("test_send_error.js") +
+                     "'></" + "script>";
+  }
 
   var error_frame = createFrame('error', html);
   var itemsTag = document.getElementById('items');
@@ -164,15 +141,12 @@ function handleFeedParsingFailed(error) {
 }
 
 function createFrame(frame_id, html) {
-  // During testing, we stuff the iframe with the script directly, so we relax
-  // the policy on running scripts under that scenario.
-  var csp = synchronousRequest ?
-      '<meta http-equiv="content-security-policy" ' +
-          'content="object-src \'none\'">' :
-      '<meta http-equiv="content-security-policy" ' +
+  var csp = '<meta http-equiv="content-security-policy" ' +
           'content="object-src \'none\'; script-src \'self\'">';
   frame = document.createElement('iframe');
   frame.id = frame_id;
+  frame.name = "preview";
+  frame.sandbox = "allow-scripts";
   frame.src = "data:text/html;charset=utf-8,<html>" + csp +
               "<!--Token:" + extension_id + token +
               "-->" + html + "</html>";

chrome/test/data/extensions/subscribe_page_action/src/test_send_error.js

+// Copyright 2020 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.
+
+// Used to communicate feed parsing errors to the testing framework.
+
+if (window.domAutomationController) {
+  window.domAutomationController.send('Error');
+}

chrome/test/data/extensions/subscribe_page_action/src/test_support.js

+// Copyright 2020 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.
+
+// Provides a default implementation for the sanitizer (a pass-through), so that
+// tests can be run on the extension directly (without having to Closure compile
+// it first).
+
+var goog = {
+  dom: {
+    safe: {
+      setAnchorHref: function(element, href) {
+        element.href = href;
+      },
+      setInnerHtml: function(element, html) {
+        element.innerHTML = html;
+      }
+    }
+  },
+  html: {
+    sanitizer: {
+      HtmlSanitizer: {
+        sanitize: function(data) {
+          return data;
+        }
+      }
+    },
+    SafeUrl: {
+      sanitize: function(data) {
+        return data;
+      }
+    }
+  },
+
+  provide: function(namespace) {},
+  require: function(namespace) {}
+};