Add //components/signin/ios/browser:unit_tests to components_unittests.

components/sessions.gypi

 # Copyright 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': {
     # Core sources shared by sessions_content and sessions_ios. These can't
     # be a separate shared library since one symbol is implemented higher up in
     # the sessions_content/ios layer.
     'sessions_core_sources': [
@@ skipping 108 matching lines @@
               'sources!': [
                'sessions/core/persistent_tab_restore_service.cc',
               ],
             },
           ],
         ],
       }],
     }, {  # OS==ios
       'targets': [
         {
+          # GN version: //components/sessions
           'target_name': 'sessions_ios',
           'type': 'static_library',
           'dependencies': [
             '../base/base.gyp:base',
             '../ios/web/ios_web.gyp:ios_web',
             '../sync/sync.gyp:sync',
             '../third_party/protobuf/protobuf.gyp:protobuf_lite',
             '../ui/base/ui_base.gyp:ui_base',
             '../ui/gfx/gfx.gyp:gfx_geometry',
             '../url/url.gyp:url_lib',
@@ skipping 14 matching lines @@
             'sessions/ios/ios_serialized_navigation_builder.h',
             'sessions/ios/ios_serialized_navigation_driver.cc',
             'sessions/ios/ios_serialized_navigation_driver.h',
           ],
         },
       ],
     }],
   ],
 
 }