Recreate WebrtcVideoSendStream if screen content setting is changed.

webrtc/media/engine/fakewebrtcvideoengine.h

 /*
  *  Copyright (c) 2010 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 178 matching lines @@
     if (!FindMatchingCodec(codecs_, codec))
       return nullptr;
     FakeWebRtcVideoEncoder* encoder = new FakeWebRtcVideoEncoder();
     encoders_.push_back(encoder);
     num_created_encoders_++;
     created_video_encoder_event_.Set();
     return encoder;
   }
 
   bool WaitForCreatedVideoEncoders(int num_encoders) {
-    while (created_video_encoder_event_.Wait(kEventTimeoutMs)) {
+    int64_t start_offset_ms = rtc::TimeMillis();
+    int64_t wait_time = kEventTimeoutMs;
+    do {
       if (GetNumCreatedEncoders() >= num_encoders)
         return true;
-    }
+      wait_time = kEventTimeoutMs - (rtc::TimeMillis() - start_offset_ms);
+    } while (wait_time > 0 && created_video_encoder_event_.Wait(wait_time));

[Taylor Brandstetter, 2017/02/23 00:46:49]

Why are start_offset_ms/wait_time needed?

[sprang_webrtc, 2017/02/23 15:10:14]

It was racy, so if |num_encoders| reached X before a call to
WaitForCreatedVideoEncoders(X), it would block for kEventTimeoutMs and return
false.

This update is also a little stricter and wait for a total of kEventTimeoutMs,
instead of resetting the timer for each update of the count until it reaches the
desired value.

Turns out this was actually needed for my test though, so if you feel it's
unnecessary I can remove it.

[Taylor Brandstetter, 2017/02/24 00:13:55]

Ah, I see. I think just changing it to a "do while" is sufficient though; the
stricter waiting seems unnecessary. I don't feel strongly about it though.

     return false;
   }
 
   void DestroyVideoEncoder(webrtc::VideoEncoder* encoder) override {
     rtc::CritScope lock(&crit_);
     encoders_.erase(
         std::remove(encoders_.begin(), encoders_.end(), encoder),
         encoders_.end());
     delete encoder;
   }
@@ skipping 38 matching lines @@
   rtc::Event created_video_encoder_event_;
   std::vector<cricket::VideoCodec> codecs_;
   std::vector<FakeWebRtcVideoEncoder*> encoders_ GUARDED_BY(crit_);
   int num_created_encoders_ GUARDED_BY(crit_);
   bool encoders_have_internal_sources_;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_ENGINE_FAKEWEBRTCVIDEOENGINE_H_