Revert of Refactor timing frame logic to work with encoders with inte…

…rnal sources (patchset #2 id:20001 of https://codereview.webrtc.org/2968153002/ )

Reason for revert:
Failing chromoting tests

Original issue's description:
> Refactor timing frame logic to work with encoders with internal sources
>
> BUG=webrtc:7594,webrtc:7893
>
> Review-Url: https://codereview.webrtc.org/2968153002
> Cr-Commit-Position: refs/heads/master@{#18955}
> Committed: https://chromium.googlesource.com/external/webrtc/+/a7a4535a35e2fccfab06c79d8704c1ca92970a6e

TBR=sprang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7594,webrtc:7893

Review-Url: https://codereview.webrtc.org/2980533002
Cr-Commit-Position: refs/heads/master@{#18957}

webrtc/modules/video_coding/generic_encoder.cc

@@ -216,6 +216,9 @@ EncodedImageCallback::Result VCMEncodedFrameCallback::OnEncodedImage(
     const RTPFragmentationHeader* fragmentation_header) {
   TRACE_EVENT_INSTANT1("webrtc", "VCMEncodedFrameCallback::Encoded",
                        "timestamp", encoded_image._timeStamp);
+  bool is_timing_frame = false;
+  size_t outlier_frame_size = 0;
+  int64_t encode_start_ms = -1;
   size_t simulcast_svc_idx = 0;
   if (codec_specific->codecType == kVideoCodecVP9) {
     if (codec_specific->codecSpecific.VP9.num_spatial_layers > 1)
@@ -228,18 +231,13 @@ EncodedImageCallback::Result VCMEncodedFrameCallback::OnEncodedImage(
     // TODO(ilnik): When h264 simulcast is landed, extract simulcast idx here.
   }
 
-  // Larger than current frame size, so it will not trigger timing frame as an
-  // outlier. If encoder didn't call OnFramerateChanged it will be used.
-  size_t outlier_frame_size = encoded_image._length + 1;
-  // Default best guess. If encoder didn't call OnEncodeStarted it will be used.
-  int64_t encode_start_ms = encoded_image.capture_time_ms_;
-  bool is_timing_frame = false;
   {
     rtc::CritScope crit(&timing_params_lock_);
-
-    // Encoders with internal sources do not call OnEncodeStarted and
-    // OnFrameRateChanged. |timing_frames_info_| may be not filled here.
+    // TODO(ilnik): Workaround for hardware encoders, which do not call
+    // |OnEncodeStarted| correctly. Once fixed, remove conditional check.
     if (simulcast_svc_idx < timing_frames_info_.size()) {
+      RTC_CHECK_LT(simulcast_svc_idx, timing_frames_info_.size());
+
       auto encode_start_map =
           &timing_frames_info_[simulcast_svc_idx].encode_start_time_ms;
       auto it = encode_start_map->find(encoded_image.capture_time_ms_);
@@ -251,43 +249,45 @@ EncodedImageCallback::Result VCMEncodedFrameCallback::OnEncodedImage(
         encode_start_map->erase(encode_start_map->begin(), it);
         encode_start_map->erase(it);
       } else {
-        // Encoder is with internal source: free our records of any frames just
-        // in case to free memory.
-        encode_start_map->clear();
+        // Some chromium remoting unittests use generic encoder incorrectly
+        // If timestamps do not match, purge them all.
+        encode_start_map->erase(encode_start_map->begin(),
+                                encode_start_map->end());
       }
 
-      size_t target_bitrate =
-          timing_frames_info_[simulcast_svc_idx].target_bitrate_bytes_per_sec;
-      if (framerate_ > 0 && target_bitrate > 0) {
-        // framerate and target bitrate were reported by encoder.
-        size_t average_frame_size = target_bitrate / framerate_;
+      int64_t timing_frame_delay_ms =
+          encoded_image.capture_time_ms_ - last_timing_frame_time_ms_;
+      if (last_timing_frame_time_ms_ == -1 ||
+          timing_frame_delay_ms >= timing_frames_thresholds_.delay_ms ||
+          timing_frame_delay_ms == 0) {
+        is_timing_frame = true;
+        last_timing_frame_time_ms_ = encoded_image.capture_time_ms_;
+      }
+      // TODO(ilnik): Once OnFramerateChanged is called correctly by hardware
+      // encoders, remove the conditional check below.
+      if (framerate_ > 0) {
+        RTC_CHECK_GT(framerate_, 0);
+        size_t average_frame_size =
+            timing_frames_info_[simulcast_svc_idx].target_bitrate_bytes_per_sec
+            / framerate_;
         outlier_frame_size = average_frame_size *
             timing_frames_thresholds_.outlier_ratio_percent /
             100;
+      } else {
+        outlier_frame_size = encoded_image._length + 1;
       }
-    }
-
-    // Check if it's time to send a timing frame.
-    int64_t timing_frame_delay_ms =
-        encoded_image.capture_time_ms_ - last_timing_frame_time_ms_;
-    // Trigger threshold if it's a first frame, too long passed since the last
-    // timing frame, or we already sent timing frame on a different simulcast
-    // stream with the same capture time.
-    if (last_timing_frame_time_ms_ == -1 ||
-        timing_frame_delay_ms >= timing_frames_thresholds_.delay_ms ||
-        timing_frame_delay_ms == 0) {
-      is_timing_frame = true;
-      last_timing_frame_time_ms_ = encoded_image.capture_time_ms_;
-    }
-
-    // Outliers trigger timing frames, but do not affect scheduled timing
-    // frames.
-    if (encoded_image._length >= outlier_frame_size) {
-      is_timing_frame = true;
+    } else {
+      // We don't have any information prior to encode start, thus we can't
+      // reliably detect outliers. Set outlier size to anything larger than
+      // current frame size.
+      outlier_frame_size = encoded_image._length + 1;
     }
   }
 
-  if (is_timing_frame) {
+  if (encoded_image._length >= outlier_frame_size) {
+    is_timing_frame = true;
+  }
+  if (encode_start_ms >= 0 && is_timing_frame) {
     encoded_image.SetEncodeTime(encode_start_ms, rtc::TimeMillis());
   }