Revert "Add fine grained dropped video frames counters on sending side"

This reverts commit 4b1a363e4c238f2e1ec2d8a9ce1f819f59d710ce.

Reason for revert: Breaks dependent android projects.

Original change's description:
> Add fine grained dropped video frames counters on sending side
> 
> 4 new counters added to SendStatisticsProxy and reported to UMA and logs.
> 
> Bug: webrtc:8355
> Change-Id: Idf9b8dfc295c92821e058a97cb3894dc6a446082
> Reviewed-on: https://webrtc-review.googlesource.com/12260
> Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
> Reviewed-by: Stefan Holmer <stefan@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#20347}

TBR=deadbeef@webrtc.org,ilnik@webrtc.org,sprang@webrtc.org,stefan@webrtc.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: webrtc:8355
Change-Id: I59b02f4eb77abad7ff1fbcbfa61844918c95d723
Reviewed-on: https://webrtc-review.googlesource.com/14500
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20378}
diff --git a/modules/video_coding/generic_encoder.cc b/modules/video_coding/generic_encoder.cc
index 5066ba1..c4affcf 100644
--- a/modules/video_coding/generic_encoder.cc
+++ b/modules/video_coding/generic_encoder.cc
@@ -216,20 +216,8 @@
   rtc::CritScope crit(&timing_params_lock_);
   if (timing_frames_info_.size() < simulcast_svc_idx + 1)
     timing_frames_info_.resize(simulcast_svc_idx + 1);
-  RTC_DCHECK(
-      timing_frames_info_[simulcast_svc_idx].encode_start_list.empty() ||
-      rtc::TimeDiff(capture_time_ms, timing_frames_info_[simulcast_svc_idx]
-                                         .encode_start_list.back()
-                                         .capture_time_ms) >= 0);
-  if (timing_frames_info_[simulcast_svc_idx].encode_start_list.size() ==
-      kMaxEncodeStartTimeListSize) {
-    LOG(LS_WARNING) << "Too many frames in the encode_start_list."
-                       " Did encoder stall?";
-    post_encode_callback_->OnDroppedFrame(DropReason::kDroppedByEncoder);
-    timing_frames_info_[simulcast_svc_idx].encode_start_list.pop_front();
-  }
-  timing_frames_info_[simulcast_svc_idx].encode_start_list.emplace_back(
-      capture_time_ms, rtc::TimeMillis());
+  timing_frames_info_[simulcast_svc_idx].encode_start_time_ms[capture_time_ms] =
+      rtc::TimeMillis();
 }
 
 EncodedImageCallback::Result VCMEncodedFrameCallback::OnEncodedImage(
@@ -261,22 +249,20 @@
     // OnFrameRateChanged. |timing_frames_info_| may be not filled here.
     num_simulcast_svc_streams = timing_frames_info_.size();
     if (simulcast_svc_idx < num_simulcast_svc_streams) {
-      auto encode_start_list =
-          &timing_frames_info_[simulcast_svc_idx].encode_start_list;
-      // Skip frames for which there was OnEncodeStarted but no OnEncodedImage
-      // call. These are dropped by encoder internally.
-      while (!encode_start_list->empty() &&
-             encode_start_list->front().capture_time_ms <
-                 encoded_image.capture_time_ms_) {
-        post_encode_callback_->OnDroppedFrame(DropReason::kDroppedByEncoder);
-        encode_start_list->pop_front();
-      }
-      if (encode_start_list->size() > 0 &&
-          encode_start_list->front().capture_time_ms ==
-              encoded_image.capture_time_ms_) {
-        encode_start_ms.emplace(
-            encode_start_list->front().encode_start_time_ms);
-        encode_start_list->pop_front();
+      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_);
+      if (it != encode_start_map->end()) {
+        encode_start_ms.emplace(it->second);
+        // Assuming all encoders do not reorder frames within single stream,
+        // there may be some dropped frames with smaller timestamps. These
+        // should be purged.
+        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();
       }
 
       size_t target_bitrate =
diff --git a/modules/video_coding/generic_encoder.h b/modules/video_coding/generic_encoder.h
index 2cdf664..9b003d6 100644
--- a/modules/video_coding/generic_encoder.h
+++ b/modules/video_coding/generic_encoder.h
@@ -12,7 +12,7 @@
 #define MODULES_VIDEO_CODING_GENERIC_ENCODER_H_
 
 #include <stdio.h>
-#include <list>
+#include <map>
 #include <vector>
 
 #include "modules/video_coding/include/video_codec_interface.h"
@@ -71,16 +71,9 @@
   EncodedImageCallback* const post_encode_callback_;
   media_optimization::MediaOptimization* const media_opt_;
 
-  struct EncodeStartTimeRecord {
-    EncodeStartTimeRecord(int64_t capture_time, int64_t encode_start_time)
-        : capture_time_ms(capture_time),
-          encode_start_time_ms(encode_start_time) {}
-    int64_t capture_time_ms;
-    int64_t encode_start_time_ms;
-  };
   struct TimingFramesLayerInfo {
     size_t target_bitrate_bytes_per_sec = 0;
-    std::list<EncodeStartTimeRecord> encode_start_list;
+    std::map<int64_t, int64_t> encode_start_time_ms;
   };
   // Separate instance for each simulcast stream or spatial layer.
   std::vector<TimingFramesLayerInfo> timing_frames_info_
@@ -118,6 +111,7 @@
   int32_t SetPeriodicKeyFrames(bool enable);
   int32_t RequestFrame(const std::vector<FrameType>& frame_types);
   bool InternalSource() const;
+  void OnDroppedFrame();
   bool SupportsNativeHandle() const;
 
  private:
diff --git a/modules/video_coding/generic_encoder_unittest.cc b/modules/video_coding/generic_encoder_unittest.cc
index 9c879e3..90d3c05 100644
--- a/modules/video_coding/generic_encoder_unittest.cc
+++ b/modules/video_coding/generic_encoder_unittest.cc
@@ -27,8 +27,7 @@
 
 class FakeEncodedImageCallback : public EncodedImageCallback {
  public:
-  FakeEncodedImageCallback()
-      : last_frame_was_timing_(false), num_frames_dropped_(0) {}
+  FakeEncodedImageCallback() : last_frame_was_timing_(false) {}
   Result OnEncodedImage(const EncodedImage& encoded_image,
                         const CodecSpecificInfo* codec_specific_info,
                         const RTPFragmentationHeader* fragmentation) override {
@@ -37,15 +36,10 @@
     return Result(Result::OK);
   };
 
-  void OnDroppedFrame(DropReason reason) override { ++num_frames_dropped_; }
-
   bool WasTimingFrame() { return last_frame_was_timing_; }
 
-  size_t GetNumFramesDropped() { return num_frames_dropped_; }
-
  private:
   bool last_frame_was_timing_;
-  size_t num_frames_dropped_;
 };
 
 enum class FrameType {
@@ -196,34 +190,5 @@
   EXPECT_FALSE(sink.WasTimingFrame());
 }
 
-TEST(TestVCMEncodedFrameCallback, NotifiesAboutDroppedFrames) {
-  EncodedImage image;
-  CodecSpecificInfo codec_specific;
-  const int64_t timestamp1 = 100;
-  const int64_t timestamp2 = 110;
-  const int64_t timestamp3 = 120;
-  const int64_t timestamp4 = 130;
-  codec_specific.codecType = kVideoCodecGeneric;
-  codec_specific.codecSpecific.generic.simulcast_idx = 0;
-  FakeEncodedImageCallback sink;
-  VCMEncodedFrameCallback callback(&sink, nullptr);
-  callback.OnEncodeStarted(timestamp1, 0);
-  EXPECT_EQ(0u, sink.GetNumFramesDropped());
-  image.capture_time_ms_ = timestamp1;
-  callback.OnEncodedImage(image, &codec_specific, nullptr);
-  callback.OnEncodeStarted(timestamp2, 0);
-  // No OnEncodedImageCall for timestamp2. Yet, at this moment it's not known
-  // that frame with timestamp2 was dropped.
-  EXPECT_EQ(0u, sink.GetNumFramesDropped());
-  callback.OnEncodeStarted(timestamp3, 0);
-  image.capture_time_ms_ = timestamp3;
-  callback.OnEncodedImage(image, &codec_specific, nullptr);
-  EXPECT_EQ(1u, sink.GetNumFramesDropped());
-  callback.OnEncodeStarted(timestamp4, 0);
-  image.capture_time_ms_ = timestamp4;
-  callback.OnEncodedImage(image, &codec_specific, nullptr);
-  EXPECT_EQ(1u, sink.GetNumFramesDropped());
-}
-
 }  // namespace test
 }  // namespace webrtc
diff --git a/modules/video_coding/include/video_coding_defines.h b/modules/video_coding/include/video_coding_defines.h
index 5bf019d..7209792 100644
--- a/modules/video_coding/include/video_coding_defines.h
+++ b/modules/video_coding/include/video_coding_defines.h
@@ -45,8 +45,6 @@
   // |kDefaultOutliserFrameSizePercent| in size of average frame.
   kDefaultTimingFramesDelayMs = 200,
   kDefaultOutlierFrameSizePercent = 250,
-  // Maximum number of frames for what we store encode start timing information.
-  kMaxEncodeStartTimeListSize = 50,
 };
 
 enum VCMVideoProtection {
diff --git a/modules/video_coding/video_sender.cc b/modules/video_coding/video_sender.cc
index 5b7bcda..fd35245 100644
--- a/modules/video_coding/video_sender.cc
+++ b/modules/video_coding/video_sender.cc
@@ -324,8 +324,7 @@
                     << " loss rate " << encoder_params.loss_rate << " rtt "
                     << encoder_params.rtt << " input frame rate "
                     << encoder_params.input_frame_rate;
-    post_encode_callback_->OnDroppedFrame(
-        EncodedImageCallback::DropReason::kDroppedByMediaOptimizations);
+    post_encode_callback_->OnDroppedFrame();
     return VCM_OK;
   }
   // TODO(pbos): Make sure setting send codec is synchronized with video