Revert "FrameGeneratorCapturer: don't generate video before Start is called"

This reverts commit 00a8576a67c9e37de52a9d0c18042b4d4fd339a2.

Reason for revert: Speculative rollback (performance metrics change)

Original change's description:
> FrameGeneratorCapturer: don't generate video before Start is called
>
> Bug: b/272350185
> Change-Id: I3c264df49e952c8f852feb08607b8d4e320b15fb
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/309860
> Reviewed-by: Jeremy Leconte <jleconte@google.com>
> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
> Commit-Queue: Artem Titov <titovartem@webrtc.org>
> Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
> Reviewed-by: Florent Castelli <orphis@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#40336}

Bug: b/272350185, b/288515909
Change-Id: I66fc61d5d4d1c17f46f1f5b4fc6ff64a9b2012f3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/310681
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Owners-Override: Mirko Bonadei <mbonadei@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Reviewed-by: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#40372}

call/bitrate_estimator_tests.cc

@@ -186,7 +186,6 @@ class BitrateEstimatorTest : public test::CallTest {
               test::VideoTestConstants::kDefaultFramerate,
               *test->task_queue_factory_);
       frame_generator_capturer_->Init();
-      frame_generator_capturer_->Start();
       send_stream_->SetSource(frame_generator_capturer_.get(),
                               DegradationPreference::MAINTAIN_FRAMERATE);
       send_stream_->Start();

pc/peer_connection_field_trial_tests.cc

@@ -237,7 +237,6 @@ TEST_F(PeerConnectionFieldTrialTest, ApplyFakeNetworkConfig) {
   auto video_track_source =
       rtc::make_ref_counted<FrameGeneratorCapturerVideoTrackSource>(
           config, clock_, /*is_screencast=*/false);
-  video_track_source->Start();
   caller->AddTrack(pc_factory_->CreateVideoTrack(video_track_source, "v"));
   WrapperPtr callee = CreatePeerConnection();
 

pc/test/frame_generator_capturer_video_track_source.h

@@ -64,15 +64,9 @@ class FrameGeneratorCapturerVideoTrackSource : public VideoTrackSource {
 
   ~FrameGeneratorCapturerVideoTrackSource() = default;
 
-  void Start() {
-    SetState(kLive);
-    video_capturer_->Start();
-  }
+  void Start() { SetState(kLive); }
 
-  void Stop() {
-    SetState(kMuted);
-    video_capturer_->Stop();
-  }
+  void Stop() { SetState(kMuted); }
 
   bool is_screencast() const override { return is_screencast_; }
 

test/BUILD.gn

@@ -1260,7 +1260,6 @@ if (!build_with_chromium) {
       ":run_loop",
       ":scoped_key_value_config",
       ":test_support",
-      ":test_video_capturer",
       ":video_test_common",
       ":video_test_constants",
       "../api:array_view",

test/call_test.cc

@@ -634,14 +634,7 @@ void CallTest::Start() {
     audio_recv_stream->Start();
 }
 
-void CallTest::StartVideoSources() {
-  for (size_t i = 0; i < video_sources_.size(); ++i) {
-    video_sources_[i]->Start();
-  }
-}
-
 void CallTest::StartVideoStreams() {
-  StartVideoSources();
   for (size_t i = 0; i < video_send_streams_.size(); ++i) {
     std::vector<bool> active_rtp_streams(
         video_send_configs_[i].rtp.ssrcs.size(), true);

test/call_test.h

@@ -36,7 +36,6 @@
 #include "test/rtp_rtcp_observer.h"
 #include "test/run_loop.h"
 #include "test/scoped_key_value_config.h"
-#include "test/test_video_capturer.h"
 #include "test/video_test_constants.h"
 
 namespace webrtc {
@@ -163,7 +162,6 @@ class CallTest : public ::testing::Test, public RtpPacketSinkInterface {
   void ConnectVideoSourcesToStreams();
 
   void Start();
-  void StartVideoSources();
   void StartVideoStreams();
   void Stop();
   void StopVideoStreams();
@@ -212,7 +210,8 @@ class CallTest : public ::testing::Test, public RtpPacketSinkInterface {
   std::vector<FlexfecReceiveStream*> flexfec_receive_streams_;
 
   test::FrameGeneratorCapturer* frame_generator_capturer_;
-  std::vector<std::unique_ptr<TestVideoCapturer>> video_sources_;
+  std::vector<std::unique_ptr<rtc::VideoSourceInterface<VideoFrame>>>
+      video_sources_;
   DegradationPreference degradation_preference_ =
       DegradationPreference::MAINTAIN_FRAMERATE;
 

test/frame_generator_capturer.cc

@@ -43,7 +43,7 @@ FrameGeneratorCapturer::FrameGeneratorCapturer(
     int target_fps,
     TaskQueueFactory& task_queue_factory)
     : clock_(clock),
-      sending_(false),
+      sending_(true),
       sink_wants_observer_(nullptr),
       frame_generator_(std::move(frame_generator)),
       source_fps_(target_fps),

test/pc/e2e/peer_connection_quality_test_test.cc

@@ -129,7 +129,7 @@ TEST_F(PeerConnectionE2EQualityTestTest, OutputVideoIsDumpedWhenRequested) {
 
   auto frame_reader = test::CreateY4mFrameReader(
       test::JoinFilename(test_directory_, "alice_video_bob_320x180_15.y4m"));
-  EXPECT_THAT(frame_reader->num_frames(), Eq(30));  // 2 seconds 15 fps
+  EXPECT_THAT(frame_reader->num_frames(), Eq(31));  // 2 seconds 15 fps + 1
 
   ExpectOutputFilesCount(1);
 }

test/peer_scenario/peer_scenario_client.cc

@@ -338,7 +338,6 @@ PeerScenarioClient::VideoSendTrack PeerScenarioClient::CreateVideo(
   capturer->Init();
   res.source = rtc::make_ref_counted<FrameGeneratorCapturerVideoTrackSource>(
       std::move(capturer), config.screencast);
-  res.source->Start();
   auto track = pc_factory_->CreateVideoTrack(res.source, track_id);
   res.track = track.get();
   res.sender =

test/scenario/video_stream.cc

@@ -419,7 +419,6 @@ SendVideoStream::SendVideoStream(CallClient* sender,
   send_config.suspend_below_min_bitrate =
       config.encoder.suspend_below_min_bitrate;
 
-  video_capturer_->Start();
   sender_->SendTask([&] {
     if (config.stream.fec_controller_factory) {
       send_stream_ = sender_->call_->CreateVideoSendStream(

video/end_to_end_tests/multi_codec_receive_tests.cc

@@ -254,7 +254,6 @@ void MultiCodecReceiveTest::RunTestWithCodecs(
       GetVideoSendStream()->Start();
       CreateFrameGeneratorCapturer(kFps, kWidth / 2, kHeight / 2);
       ConnectVideoSourcesToStreams();
-      StartVideoSources();
     });
     EXPECT_TRUE(observer_.Wait()) << "Timed out waiting for frames.";
   }

video/end_to_end_tests/rtp_rtcp_tests.cc

@@ -339,7 +339,6 @@ void RtpRtcpEndToEndTest::TestRtpStatePreservation(
             ->SendRtcp(packet.data(), packet.size());
       }
       CreateFrameGeneratorCapturer(30, 1280, 720);
-      StartVideoSources();
     });
 
     observer.ResetExpectedSsrcs(1);