Reason for revert:
Create fix CL.
Original issue's description:
> 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}
> Committed: 77a983185fTBR=terelius@webrtc.org,stefan@webrtc.org,noahric@chromium.org,deadbeef@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
BUG=webrtc:8074
Review-Url: https://codereview.webrtc.org/2996823002
Cr-Commit-Position: refs/heads/master@{#19324}
628ac5964e