Let IPC::SyncMessageFilter take advantage of thread-safe Send.

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 143 matching lines @@
       'test/test_render_frame.cc',
       'test/test_render_frame.h',
       'test/test_render_frame_host.cc',
       'test/test_render_frame_host.h',
       'test/test_render_frame_host_factory.cc',
       'test/test_render_frame_host_factory.h',
       'test/test_render_view_host.cc',
       'test/test_render_view_host.h',
       'test/test_render_view_host_factory.cc',
       'test/test_render_view_host_factory.h',
+      'test/test_thread_safe_sender.cc',
+      'test/test_thread_safe_sender.h',
       'test/test_web_contents.cc',
       'test/test_web_contents.h',
       'test/test_web_contents_factory.cc',
       'test/web_contents_observer_sanity_checker.cc',
       'test/web_contents_observer_sanity_checker.h',
       'test/web_gesture_curve_mock.cc',
       'test/web_gesture_curve_mock.h',
       'test/web_layer_tree_view_impl_for_testing.cc',
       'test/web_layer_tree_view_impl_for_testing.h',
       'test/weburl_loader_mock.cc',
@@ skipping 617 matching lines @@
           ],
           'sources': [ '<@(layouttest_support_content_sources)' ]
         }],
       ],
     },
     {
       # GN version: //content/test:test_support
       'target_name': 'test_support_content',
       'type': 'static_library',
       'dependencies': [
+        '../ipc/ipc.gyp:ipc',
         '../mojo/mojo_base.gyp:mojo_application_base',
         '../mojo/mojo_base.gyp:mojo_environment_chromium',
         '../net/net.gyp:net_test_support',
         '../skia/skia.gyp:skia',
         '../storage/storage_common.gyp:storage_common',
         '../testing/gmock.gyp:gmock',
         '../testing/gtest.gyp:gtest',
         '../third_party/mojo/mojo_edk.gyp:mojo_system_impl',
         '../third_party/mojo/mojo_public.gyp:mojo_cpp_bindings',
         '../ui/accessibility/accessibility.gyp:ax_gen',
@@ skipping 1293 matching lines @@
             ],
           },
           'includes': [
             '../build/host_jar.gypi',
           ],
         },
       ],
     }],
   ],
 }