Remove WebRTC-videocontenttypeextension field trial completely

webrtc/video/video_send_stream_tests.cc

 /*
  *  Copyright (c) 2013 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.
  */
 #include <algorithm>  // max
@@ skipping 322 matching lines @@
           RtpExtension(RtpExtension::kVideoContentTypeUri,
                        test::kVideoContentTypeExtensionId));
       encoder_config->content_type = VideoEncoderConfig::ContentType::kScreen;
     }
 
     void PerformTest() override {
       EXPECT_TRUE(Wait()) << "Timed out while waiting for single RTP packet.";
     }
   } test;
 
-  test::ScopedFieldTrials override_field_trials(
-      "WebRTC-VideoContentTypeExtension/Enabled/");
   RunBaseTest(&test);
 }
 
 TEST_F(VideoSendStreamTest, SupportsVideoTimingFrames) {
   class VideoTimingObserver : public test::SendTest {
    public:
     VideoTimingObserver() : SendTest(kDefaultTimeoutMs) {
       EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(
           kRtpExtensionVideoTiming, test::kVideoTimingExtensionId));
     }
@@ skipping 3137 matching lines @@
       capturer_ = frame_generator_capturer;
     }
 
     test::FrameGeneratorCapturer* capturer_ = nullptr;
   } test;
 
   RunBaseTest(&test);
 }
 
 }  // namespace webrtc