Recreate WebrtcVideoSendStream if screen content setting is changed.

webrtc/media/engine/webrtcvideoengine2.h

Index: webrtc/media/engine/webrtcvideoengine2.h
diff --git a/webrtc/media/engine/webrtcvideoengine2.h b/webrtc/media/engine/webrtcvideoengine2.h
index 7043e031a4ebcf5785625289328f9459aca7d21b..309a84d924d1474233587c8cbd420837427a95e6 100644
--- a/webrtc/media/engine/webrtcvideoengine2.h
+++ b/webrtc/media/engine/webrtcvideoengine2.h
@@ -306,9 +306,14 @@ class WebRtcVideoChannel2 : public VideoMediaChannel, public webrtc::Transport {
 
     rtc::scoped_refptr<webrtc::VideoEncoderConfig::EncoderSpecificSettings>
     ConfigureVideoEncoderSettings(const VideoCodec& codec);
-    AllocatedEncoder CreateVideoEncoder(const VideoCodec& codec);
+    // If force_encoder_allocation is true, a new AllocatedEncoder is always
+    // created. If false, the allocated encoder may be reused, if the type
+    // matches.
+    AllocatedEncoder CreateVideoEncoder(const VideoCodec& codec,
+                                        bool force_encoder_allocation);
     void DestroyVideoEncoder(AllocatedEncoder* encoder);
-    void SetCodec(const VideoCodecSettings& codec);
+    void SetCodec(const VideoCodecSettings& codec,
+                  bool force_encoder_allocation);
     void RecreateWebRtcStream();
     webrtc::VideoEncoderConfig CreateVideoEncoderConfig(
         const VideoCodec& codec) const;