Convert app_shell_unittests to run on Swarming

extensions/shell/app_shell.gyp

 # Copyright 2014 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.
 
 {
   'includes': [
     'app_shell.gypi',
   ],
   'variables': {
     # Product name is used for Mac bundle.
@@ skipping 406 matching lines @@
               # executable.
               'postbuild_name': 'Verify No Objective-C',
               'action': [
                 '../../build/mac/verify_no_objc.sh',
               ],
             },
           ],
         },  # target app_shell_helper
       ],
     }],  # OS=="mac"
+    ['test_isolation_mode != "noop"', {
+      'targets': [
+        {
+          'target_name': 'app_shell_unittests_run',
+          'type': 'none',
+          'dependencies': [
+            'app_shell_unittests',
+          ],
+          'includes': [
+            '../../build/isolate.gypi',
+          ],
+          'sources': [
+            'app_shell_unittests.isolate',
+          ],
+        },
+      ],
+    }],
   ],
 }