Add isolate for content_browsertests with --site-per-process.

content/content_tests.gypi

 # Copyright (c) 2013 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.
 
 {
   'variables': {
     'layouttest_support_content_sources': [
       'public/test/layouttest_support.h',
       'public/test/nested_message_pump_android.cc',
       'public/test/nested_message_pump_android.h',
@@ skipping 1004 matching lines @@
             '../gin/gin.gyp:gin',
           ],
         }],
       ],
     },
   ],
   'conditions': [
     ['test_isolation_mode != "noop"', {
       'targets': [
         {
+          # GN: //content/test:content_site_isolation_browsertests_run
+          'target_name': 'content_site_isolation_browsertests_run',
+          'type': 'none',
+          'dependencies': [
+            'content_browsertests_run',
+          ],
+          'sources': [
+            'content_site_isolation_browsertests.isolate',
+          ],
+        },
+        {
           'target_name': 'content_browsertests_run',
           'type': 'none',
           'dependencies': [
             'content_browsertests',
           ],
           'includes': [
             '../build/isolate.gypi',
           ],
           'sources': [
             'content_browsertests.isolate',
@@ skipping 1184 matching lines @@
                   'content_unittests_apk.isolate',
                 ],
               },
             ],
           },
         ],
       ],
     }],
   ],
 }