Set screenshare.enabled parameter to false when running video_loopback test.

webrtc/video/video_loopback.cc

 /*
  *  Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 235 matching lines @@
                    flags::FLAGS_suspend_below_min_bitrate,
                    flags::Codec(),
                    flags::NumTemporalLayers(),
                    flags::SelectedTL(),
                    0,  // No min transmit bitrate.
                    flags::FLAGS_send_side_bwe,
                    flags::FLAGS_use_fec,
                    flags::EncodedFramePath(),
                    call_bitrate_config};
   params.video = {flags::Clip()};
+  params.screenshare.enabled = false;
   params.analyzer = {"video", 0.0, 0.0, flags::DurationSecs(),
       flags::OutputFilename(), flags::GraphTitle()};
   params.pipe = pipe_config;
   params.logs = flags::FLAGS_logs;
   params.audio = flags::FLAGS_audio,
   params.audio_video_sync = flags::FLAGS_audio_video_sync;
 
   std::vector<std::string> stream_descriptors;
   stream_descriptors.push_back(flags::Stream0());
   stream_descriptors.push_back(flags::Stream1());
@@ skipping 14 matching lines @@
 }  // namespace webrtc
 
 int main(int argc, char* argv[]) {
   ::testing::InitGoogleTest(&argc, argv);
   google::ParseCommandLineFlags(&argc, &argv, true);
   webrtc::test::InitFieldTrialsFromString(
       webrtc::flags::FLAGS_force_fieldtrials);
   webrtc::test::RunTest(webrtc::Loopback);
   return 0;
 }