Enabling spatial layers in VP9Impl. Filter layers in the loopback test.

webrtc/video/loopback.h

 /*
  *  Copyright (c) 2015 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 15 matching lines @@
   struct Config {
     size_t width;
     size_t height;
     int32_t fps;
     size_t min_bitrate_kbps;
     size_t start_bitrate_kbps;
     size_t max_bitrate_kbps;
     int32_t min_transmit_bitrate_kbps;
     std::string codec;
     size_t num_temporal_layers;
+    size_t num_spatial_layers;
+    // Discard all temporal/spatial layers with id greater or equal the
+    // threshold. 0 to disable.
+    size_t tl_discard_threshold;
+    size_t sl_discard_threshold;
     int32_t loss_percent;
     int32_t link_capacity_kbps;
     int32_t queue_size;
     int32_t avg_propagation_delay_ms;
     int32_t std_propagation_delay_ms;
     bool logs;
   };
 
   explicit Loopback(const Config& config);
   virtual ~Loopback();
 
   void Run();
 
  protected:
   virtual VideoEncoderConfig CreateEncoderConfig();
   virtual VideoCapturer* CreateCapturer(VideoSendStream* send_stream);
 
   const Config config_;
   Clock* const clock_;
 };
 
 }  // namespace test
 }  // namespace webrtc