Revert of Disable flaky test VideoProcessorIntegrationTest.ProcessNoLossChangeFrameRateFrameDropVP9

webrtc/modules/video_coding/codecs/test/videoprocessor_integrationtest.cc

 /*
  *  Copyright (c) 2012 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 684 matching lines @@
                          rc_metrics);
 }
 
 // VP9: Run with no packet loss, with an update (decrease) in frame rate.
 // Lower frame rate means higher per-frame-bandwidth, so easier to encode.
 // At the low bitrate in this test, this means better rate control after the
 // update(s) to lower frame rate. So expect less frame drops, and max values
 // for the rate control metrics can be lower. One key frame (first frame only).
 // Note: quality after update should be higher but we currently compute quality
 // metrics averaged over whole sequence run.
-
-
-// Flaky https://bugs.chromium.org/p/webrtc/issues/detail?id=6057.
 TEST_F(VideoProcessorIntegrationTest,
-       DISABLED_ProcessNoLossChangeFrameRateFrameDropVP9) {
+       ProcessNoLossChangeFrameRateFrameDropVP9) {
   config_.networking_config.packet_loss_probability = 0;
   // Bitrate and frame rate profile.
   RateProfile rate_profile;
   SetRateProfilePars(&rate_profile, 0, 100, 24, 0);
   SetRateProfilePars(&rate_profile, 1, 100, 15, 100);
   SetRateProfilePars(&rate_profile, 2, 100, 10, 200);
   rate_profile.frame_index_rate_update[3] = kNbrFramesLong + 1;
   rate_profile.num_frames = kNbrFramesLong;
   // Codec/network settings.
   CodecConfigPars process_settings;
@@ skipping 244 matching lines @@
   QualityMetrics quality_metrics;
   SetQualityMetrics(&quality_metrics, 32.5, 30.0, 0.85, 0.80);
   // Metrics for rate control.
   RateControlMetrics rc_metrics[2];
   SetRateControlMetrics(rc_metrics, 0, 0, 20, 30, 10, 10, 0, 1);
   SetRateControlMetrics(rc_metrics, 1, 0, 0, 30, 15, 10, 0, 0);
   ProcessFramesAndVerify(quality_metrics, rate_profile, process_settings,
                          rc_metrics);
 }
 }  // namespace webrtc