GitLab

    
Webrtc unfortunately likes to sleep in BaseChannel::Send on the renderer's
ChildThread while directly or indirectly calling into HW encoder and we end 
up in a number of deadlocks of varying complexity in one way or another,
while trying to also use the ChildThread to allocate shared memory to service 
those calls.
The only way to avoid this is to not get onto the ChildThread while servicing
webrtc requests, so we use the static ChildThread::AllocateSharedMemory()
to send the request directly from the current thread.
    
Also add VEA::RequireBitstreamBuffers() to the initialization sequence, so that
RTCVideoEncoder::InitEncode() will only return after we've allocated requested
buffers. VEA::RequireBitstreamBuffers() is effectively a part of initialization
sequence anyway, because we can't really call VEA::Encode() without knowing the
VEA impl's coded size requirements. This could also potentially reduce
the latency of the first Encode() call.

And separately, zero out header structures sent to the client.

TEST=apprtc.appspot.com with HW encoding
BUG=260210

Review URL: https://chromiumcodereview.appspot.com/23440015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@221395 0039d316-1c4b-4281-b951-d872f2087c98