Revert of Request keyframes more frequently on stream start/decoding error. (patchset #1 id:1 of https://codereview.webrtc.org/2993793002/ )

Reason for revert:
Broke downstream test that was waiting for 5 keyframes to be received within 10 seconds. Maybe the issue is that "stats_callback_->OnCompleteFrame(frame->num_references == 0, ..." was changed to "frame->is_keyframe()"?

Original issue's description:
> Request keyframes more frequently on stream start/decoding error.
>
> In this CL:
>  - Added FrameObject::is_keyframe() convinience function.
>  - Moved logic to request keyframes on decoding error from VideoReceived to
>    VideoReceiveStream.
>  - Added keyframe_required as a parameter to FrameBuffer::NextFrame.
>
> BUG=webrtc:8074
>
> Review-Url: https://codereview.webrtc.org/2993793002
> Cr-Commit-Position: refs/heads/master@{#19280}
> Committed: 26b4804358

TBR=terelius@webrtc.org,stefan@webrtc.org,noahric@chromium.org,philipel@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:8074

Review-Url: https://codereview.webrtc.org/2994043002
Cr-Commit-Position: refs/heads/master@{#19295}

webrtc/modules/video_coding/frame_buffer2.cc

@@ -59,8 +59,7 @@ FrameBuffer::~FrameBuffer() {}
 
 FrameBuffer::ReturnReason FrameBuffer::NextFrame(
     int64_t max_wait_time_ms,
-    std::unique_ptr<FrameObject>* frame_out,
-    bool keyframe_required) {
+    std::unique_ptr<FrameObject>* frame_out) {
   TRACE_EVENT0("webrtc", "FrameBuffer::NextFrame");
   int64_t latest_return_time_ms =
       clock_->TimeInMilliseconds() + max_wait_time_ms;
@@ -106,10 +105,6 @@ FrameBuffer::ReturnReason FrameBuffer::NextFrame(
         }
 
         FrameObject* frame = frame_it->second.frame.get();
-
-        if (keyframe_required && !frame->is_keyframe())
-          continue;
-
         next_frame_it_ = frame_it;
         if (frame->RenderTime() == -1)
           frame->SetRenderTime(timing_->RenderTimeMs(frame->timestamp, now_ms));
@@ -284,7 +279,7 @@ int FrameBuffer::InsertFrame(std::unique_ptr<FrameObject> frame) {
   TRACE_EVENT0("webrtc", "FrameBuffer::InsertFrame");
   RTC_DCHECK(frame);
   if (stats_callback_)
-    stats_callback_->OnCompleteFrame(frame->is_keyframe(), frame->size());
+    stats_callback_->OnCompleteFrame(frame->num_references == 0, frame->size());
   FrameKey key(frame->picture_id, frame->spatial_layer);
 
   rtc::CritScope lock(&crit_);
@@ -312,7 +307,7 @@ int FrameBuffer::InsertFrame(std::unique_ptr<FrameObject> frame) {
   if (last_decoded_frame_it_ != frames_.end() &&
       key <= last_decoded_frame_it_->first) {
     if (AheadOf(frame->timestamp, last_decoded_frame_timestamp_) &&
-        frame->is_keyframe()) {
+        frame->num_references == 0) {
       // If this frame has a newer timestamp but an earlier picture id then we
       // assume there has been a jump in the picture id due to some encoder
       // reconfiguration or some other reason. Even though this is not according

webrtc/modules/video_coding/frame_buffer2.h

@@ -57,8 +57,7 @@ class FrameBuffer {
   //    kTimeout.
   //  - If the FrameBuffer is stopped then it will return kStopped.
   ReturnReason NextFrame(int64_t max_wait_time_ms,
-                         std::unique_ptr<FrameObject>* frame_out,
-                         bool keyframe_required = false);
+                         std::unique_ptr<FrameObject>* frame_out);
 
   // Tells the FrameBuffer which protection mode that is in use. Affects
   // the frame timing.

webrtc/modules/video_coding/frame_buffer2_unittest.cc

@@ -167,12 +167,11 @@ class TestFrameBuffer2 : public ::testing::Test {
     return buffer_.InsertFrame(std::move(frame));
   }
 
-  void ExtractFrame(int64_t max_wait_time = 0, bool keyframe_required = false) {
+  void ExtractFrame(int64_t max_wait_time = 0) {
     crit_.Enter();
     if (max_wait_time == 0) {
       std::unique_ptr<FrameObject> frame;
-      FrameBuffer::ReturnReason res =
-          buffer_.NextFrame(0, &frame, keyframe_required);
+      FrameBuffer::ReturnReason res = buffer_.NextFrame(0, &frame);
       if (res != FrameBuffer::ReturnReason::kStopped)
         frames_.emplace_back(std::move(frame));
       crit_.Leave();
@@ -541,18 +540,5 @@ TEST_F(TestFrameBuffer2, InvalidReferences) {
   EXPECT_EQ(2, InsertFrame(2, 0, 3000, false, 1));
 }
 
-TEST_F(TestFrameBuffer2, KeyframeRequired) {
-  EXPECT_EQ(1, InsertFrame(1, 0, 1000, false));
-  EXPECT_EQ(2, InsertFrame(2, 0, 2000, false, 1));
-  EXPECT_EQ(3, InsertFrame(3, 0, 3000, false));
-  ExtractFrame();
-  ExtractFrame(0, true);
-  ExtractFrame();
-
-  CheckFrame(0, 1, 0);
-  CheckFrame(1, 3, 0);
-  CheckNoFrame(2);
-}
-
 }  // namespace video_coding
 }  // namespace webrtc

webrtc/modules/video_coding/frame_object.h

@@ -44,8 +44,6 @@ class FrameObject : public webrtc::VCMEncodedFrame {
 
   size_t size() const { return _length; }
 
-  bool is_keyframe() const { return num_references == 0; }
-
   // The tuple (|picture_id|, |spatial_layer|) uniquely identifies a frame
   // object. For codec types that don't necessarily have picture ids they
   // have to be constructed from the header data relevant to that codec.

webrtc/modules/video_coding/video_receiver.cc

@@ -320,7 +320,24 @@ int32_t VideoReceiver::Decode(const VCMEncodedFrame& frame) {
   if (decoder == nullptr) {
     return VCM_NO_CODEC_REGISTERED;
   }
-  return decoder->Decode(frame, clock_->TimeInMilliseconds());
+  // Decode a frame
+  int32_t ret = decoder->Decode(frame, clock_->TimeInMilliseconds());
+
+  // Check for failed decoding, run frame type request callback if needed.
+  bool request_key_frame = false;
+  if (ret < 0) {
+    request_key_frame = true;
+  }
+
+  if (!frame.Complete() || frame.MissingFrame()) {
+    request_key_frame = true;
+    ret = VCM_OK;
+  }
+  if (request_key_frame) {
+    rtc::CritScope cs(&process_crit_);
+    _scheduleKeyRequest = true;
+  }
+  return ret;
 }
 
 // Register possible receive codecs, can be called multiple times