Make protocol::ConnectionToClient an abstract interface.

remoting/remoting_test.gypi

Index: remoting/remoting_test.gypi
diff --git a/remoting/remoting_test.gypi b/remoting/remoting_test.gypi
index 67020539e25a11918e5ed79bd06edb46041d56a6..21efd2e423a5f1fb5d3dc4ec60409be0c0dc2818 100644
--- a/remoting/remoting_test.gypi
+++ b/remoting/remoting_test.gypi
@@ -311,8 +311,8 @@
         'protocol/clipboard_filter_unittest.cc',
         'protocol/connection_tester.cc',
         'protocol/connection_tester.h',
-        'protocol/connection_to_client_unittest.cc',
         'protocol/content_description_unittest.cc',
+        'protocol/ice_connection_to_client_unittest.cc',
         'protocol/input_event_tracker_unittest.cc',
         'protocol/input_filter_unittest.cc',
         'protocol/jingle_messages_unittest.cc',
@@ -321,12 +321,12 @@
         'protocol/message_reader_unittest.cc',
         'protocol/monitored_video_stub_unittest.cc',
         'protocol/mouse_input_filter_unittest.cc',
-        'protocol/quic_channel_factory_unittest.cc',
         'protocol/negotiating_authenticator_unittest.cc',
         'protocol/pairing_registry_unittest.cc',
         'protocol/port_range_unittest.cc',
         'protocol/ppapi_module_stub.cc',
         'protocol/pseudotcp_adapter_unittest.cc',
+        'protocol/quic_channel_factory_unittest.cc',
         'protocol/ssl_hmac_channel_authenticator_unittest.cc',
         'protocol/third_party_authenticator_unittest.cc',
         'protocol/v2_authenticator_unittest.cc',
@@ -337,8 +337,8 @@
         'signaling/server_log_entry_unittest.cc',
         'signaling/server_log_entry_unittest.h',
         'signaling/xmpp_login_handler_unittest.cc',
-        'signaling/xmpp_stream_parser_unittest.cc',
         'signaling/xmpp_signal_strategy_unittest.cc',
+        'signaling/xmpp_stream_parser_unittest.cc',
         'test/access_token_fetcher_unittest.cc',
         'test/app_remoting_report_issue_request_unittest.cc',
         'test/app_remoting_test_driver_environment_unittest.cc',