Revert of Remove about:srcdoc url conversion.

chrome/test/data/extensions/api_test/executescript/frame_id/test.js

 // Copyright 2016 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.
 
 var pass = chrome.test.callbackPass;
 var fail = chrome.test.callbackFail;
 var assertEq = chrome.test.assertEq;
 var assertTrue = chrome.test.assertTrue;
 var relativePath = '/extensions/api_test/executescript/frame_id/frames.html';
 var testOrigin = 'http://a.com:PORT';
@@ skipping 129 matching lines @@
             matchAboutBlank: true,
             code: 'document.URL'
           },
           pass(function(results) {
             assertEq(1, results.length);
             assertTrue(matchesAny(results, R_FRAME_SRCDOC));
           }));
     },
 
     function executeScriptInSrcdocFrameWithoutMatchAboutBlank() {
+      // TODO(robwu): Why is the origin serialized as "about:blank" instead of
+      // "about:srcdoc"?
       chrome.tabs.executeScript(
           tabId, {frameId: ID_FRAME_SRCDOC, code: 'document.URL'},
           fail(
-              'Cannot access "about:srcdoc" at origin "' + testOrigin + '". ' +
+              'Cannot access "about:blank" at origin "' + testOrigin + '". ' +
               'Extension must have permission to access the frame\'s origin, ' +
               'and matchAboutBlank must be true.'));
     },
 
     function executeScriptInSrcdocFrameIncludingAllFrames() {
       chrome.tabs.executeScript(
           tabId, {
             frameId: ID_FRAME_SRCDOC,
             matchAboutBlank: true,
             allFrames: true,
@@ skipping 110 matching lines @@
     function insertCSSInSrcdocFrame() {
       insertCSS(
           tabId, {frameId: ID_FRAME_SRCDOC, matchAboutBlank: true},
           pass(function(results) {
             assertEq(1, results.length);
             assertTrue(matchesAny(results, R_FRAME_SRCDOC));
           }));
     },
 
     function insertCSSInSrcdocFrameWithoutMatchAboutBlank() {
+      // TODO(robwu): Why is the origin serialized as "about:blank" instead of
+      // "about:srcdoc"?
       chrome.tabs.insertCSS(
           tabId, {frameId: ID_FRAME_SRCDOC, code: 'body{color:red;}'},
           fail(
-              'Cannot access "about:srcdoc" at origin "' + testOrigin + '". ' +
+              'Cannot access "about:blank" at origin "' + testOrigin + '". ' +
               'Extension must have permission to access the frame\'s origin, ' +
               'and matchAboutBlank must be true.'));
     },
 
     function insertCSSInSrcdocFrameIncludingAllFrames() {
       insertCSS(
           tabId,
           {frameId: ID_FRAME_SRCDOC, matchAboutBlank: true, allFrames: true},
           pass(function(results) {
             assertEq(1, results.length);
@@ skipping 72 matching lines @@
         assertEq(
             'Invalid value for argument 2. Property \'frameId\': ' +
                 'Value must not be less than 0.',
             e.message);
         chrome.test.succeed();
       }
     },
 
   ]);
 }