AVFoundation Video Capturer: Remove thread jump when delivering frames

webrtc/base/timestampaligner.cc

 /*
  *  Copyright (c) 2016 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 "webrtc/base/logging.h"
 #include "webrtc/base/timestampaligner.h"
 
 namespace rtc {
 
-TimestampAligner::TimestampAligner() : frames_seen_(0), offset_us_(0) {
-  thread_checker_.DetachFromThread();
-}
+TimestampAligner::TimestampAligner() : frames_seen_(0), offset_us_(0) {}
 
 TimestampAligner::~TimestampAligner() {}
 
 int64_t TimestampAligner::UpdateOffset(int64_t camera_time_us,
                                        int64_t system_time_us) {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
-
   // Estimate the offset between system monotonic time and the capture
   // time from the camera. The camera is assumed to provide more
   // accurate timestamps than we get from the system time. But the
   // camera may use its own free-running clock with a large offset and
   // a small drift compared to the system clock. So the model is
   // basically
   //
   //   y_k = c_0 + c_1 * x_k + v_k
   //
   // where x_k is the camera timestamp, believed to be accurate in its
@@ skipping 48 matching lines @@
   static const int kWindowSize = 100;
   if (frames_seen_ < kWindowSize) {
     ++frames_seen_;
   }
   offset_us_ += error_us / frames_seen_;
   return offset_us_;
 }
 
 int64_t TimestampAligner::ClipTimestamp(int64_t time_us,
                                         int64_t system_time_us) {
-  RTC_DCHECK(thread_checker_.CalledOnValidThread());
-
   // Make timestamps monotonic.
   if (!prev_translated_time_us_) {
     // Initialize.
     clip_bias_us_ = 0;
   } else if (time_us < *prev_translated_time_us_) {
     time_us = *prev_translated_time_us_;
   }
 
   // Clip to make sure we don't produce time stamps in the future.
   time_us -= clip_bias_us_;
   if (time_us > system_time_us) {
     clip_bias_us_ += time_us - system_time_us;
     time_us = system_time_us;
   }
   prev_translated_time_us_ = rtc::Optional<int64_t>(time_us);
   return time_us;
 }
 
 }  // namespace rtc