Work on flexible mode and screen sharing.

webrtc/modules/video_coding/codecs/vp9/vp9_impl.h

Index: webrtc/modules/video_coding/codecs/vp9/vp9_impl.h
diff --git a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.h b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.h
index c164a63980f2dedf54149e4f6e30477682f947e8..980b748a89011183e4a04bda1727bbfc55178e54 100644
--- a/webrtc/modules/video_coding/codecs/vp9/vp9_impl.h
+++ b/webrtc/modules/video_coding/codecs/vp9/vp9_impl.h
@@ -13,6 +13,7 @@
 #define WEBRTC_MODULES_VIDEO_CODING_CODECS_VP9_IMPL_H_
 
 #include "webrtc/modules/video_coding/codecs/vp9/include/vp9.h"
+#include "webrtc/modules/video_coding/codecs/vp9/screenshare_layers.h"
 #include "webrtc/modules/video_coding/codecs/vp9/vp9_frame_buffer_pool.h"
 
 #include "vpx/svc_context.h"
@@ -58,6 +59,30 @@ class VP9EncoderImpl : public VP9Encoder {
 
   bool SetSvcRates();
 
+  /*
+   * Generate the flags used when calling vpx_encoder_encode and also
+   * saves information used to reference this frame to earlier frames.
+   * Used in flexible mode and has to be called for every frame (even
+   * keyframes) in order to update its state. The information used
+   * for references is saved in p_diff_ and num_ref_pics_.
+   *
+   * upd_buffer - which buffer to update:
+   *       -2: this is a keyframe, always stored in buffer
+   *           0 and all other params are ignored
+   *       -1: don't update any buffers
+   *     0..2: update buffer 0..2
+   *
+   * ref_buf1, ref_buf2, ref_buf3 - which buffers to reference back to:
+   *       -1: don't reference any buffer
+   *     0..2: reference buffer 0..2
+   *
+   */
+  vpx_enc_frame_flags_t GenerateRefsAndFlags(int8_t upd_buffer = -2,
+                                             int8_t ref_buf1 = -1,
+                                             int8_t ref_buf2 = -1,
+                                             int8_t ref_buf3 = -1);
+  vpx_enc_frame_flags_t GenerateRefsAndFlags(std::array<int8_t, 4> args);
+
   virtual int GetEncodedLayerFrame(const vpx_codec_cx_pkt* pkt);
 
   // Callback function for outputting packets per spatial layer.
@@ -88,9 +113,17 @@ class VP9EncoderImpl : public VP9Encoder {
   GofInfoVP9 gof_;       // Contains each frame's temporal information for
                          // non-flexible mode.
   uint8_t tl0_pic_idx_;  // Only used in non-flexible mode.
-  size_t gof_idx_;       // Only used in non-flexible mode.
+  size_t frames_since_kf_;
   uint8_t num_temporal_layers_;
   uint8_t num_spatial_layers_;
+
+  // Used for flexible mode
+  bool is_flexible_mode_;
+  int64_t buf_upd_at_frame_[8];
+  int64_t frames_encoded_;
+  uint8_t num_refs_pics_;
+  uint8_t p_diff_[kMaxVp9RefPics];
+  ScreenshareLayersVP9 temporal_layer_;
 };