Let ViEEncoder handle resolution changes.

webrtc/config.h

Index: webrtc/config.h
diff --git a/webrtc/config.h b/webrtc/config.h
index 9303f548e7299d857447970f0208d2e476665a76..3758fc2ef3cfb7624ddef2e86b4cff0bf21d0815 100644
--- a/webrtc/config.h
+++ b/webrtc/config.h
@@ -17,6 +17,8 @@
 #include <vector>
 
 #include "webrtc/base/optional.h"
+#include "webrtc/base/refcount.h"
+#include "webrtc/base/scoped_ref_ptr.h"
 #include "webrtc/common_types.h"
 #include "webrtc/typedefs.h"
 
@@ -130,6 +132,21 @@ struct VideoEncoderConfig {
     kScreen,
   };
 
+  class VideoStreamFactoryInterface : public rtc::RefCountInterface {
+   public:
+    // An implementation should return a std::vector<VideoStream> with the
+    // wanted VideoStream settings for the given video resolution.
+    // The size of the vector may not be larger than
+    // |encoder_config.number_of_streams|.
+    virtual std::vector<VideoStream> CreateEncoderStreams(
+        int width,
+        int height,
+        const VideoEncoderConfig& encoder_config) = 0;
+
+   protected:
+    virtual ~VideoStreamFactoryInterface() {}
+  };
+
   VideoEncoderConfig& operator=(VideoEncoderConfig&&) = default;
   VideoEncoderConfig& operator=(const VideoEncoderConfig&) = delete;
 
@@ -141,7 +158,7 @@ struct VideoEncoderConfig {
   ~VideoEncoderConfig();
   std::string ToString() const;
 
-  std::vector<VideoStream> streams;
+  rtc::scoped_refptr<VideoStreamFactoryInterface> encoder_stream_factory;
   std::vector<SpatialLayer> spatial_layers;
   ContentType content_type;
   void* encoder_specific_settings;
@@ -151,7 +168,10 @@ struct VideoEncoderConfig {
   // maintaining a higher bitrate estimate. Padding will however not be sent
   // unless the estimated bandwidth indicates that the link can handle it.
   int min_transmit_bitrate_bps;
-  bool expect_encode_from_texture;
+  int max_bitrate_bps;
+
+  // Max number of encoded VideoStreams to produce.
+  size_t number_of_streams;
 
  private:
   // Access to the copy constructor is private to force use of the Copy()