[Cast] Software encoder support for varying video frame sizes.

media/cast/sender/vp8_encoder.h

Index: media/cast/sender/vp8_encoder.h
diff --git a/media/cast/sender/vp8_encoder.h b/media/cast/sender/vp8_encoder.h
index 387dbf27a4b92652f8d05a03ee042a83b7196544..2de51d4663cab8b34aa47a331a6c82302d51fd62 100644
--- a/media/cast/sender/vp8_encoder.h
+++ b/media/cast/sender/vp8_encoder.h
@@ -11,6 +11,7 @@
 #include "media/cast/cast_config.h"
 #include "media/cast/sender/software_video_encoder.h"
 #include "third_party/libvpx/source/libvpx/vpx/vpx_encoder.h"
+#include "ui/gfx/geometry/size.h"
 
 namespace media {
 class VideoFrame;
@@ -56,11 +57,17 @@ class Vp8Encoder : public SoftwareVideoEncoder {
   };
 
   bool is_initialized() const {
-    // Initialize() sets the timebase denominator value to non-zero if the
-    // encoder is successfully initialized, and it is zero otherwise.
+    // ConfigureForNewFrameSize() sets the timebase denominator value to
+    // non-zero if the encoder is successfully initialized, and it is zero
+    // otherwise.
     return config_.g_timebase.den != 0;
   }
 
+  // If the |encoder_| is live, attempt reconfiguration to allow it to encode
+  // frames at a new |frame_size|.  Otherwise, tear it down and re-create a new
+  // |encoder_| instance.
+  void ConfigureForNewFrameSize(const gfx::Size& frame_size);
+
   // Calculate which next Vp8 buffers to update with the next frame.
   Vp8Buffers GetNextBufferToUpdate();
 
@@ -80,12 +87,13 @@ class Vp8Encoder : public SoftwareVideoEncoder {
   vpx_codec_enc_cfg_t config_;
   vpx_codec_ctx_t encoder_;
 
-  // Wrapper for access to YUV data planes in a media::VideoFrame.
-  vpx_image_t* raw_image_;
-
   // Set to true to request the next frame emitted by Vp8Encoder be a key frame.
   bool key_frame_requested_;
 
+  // Saves the current bitrate setting, for when the |encoder_| is reconfigured
+  // for different frame sizes.
+  int bitrate_kbit_;
+
   // The |VideoFrame::timestamp()| of the last encoded frame.  This is used to
   // predict the duration of the next frame.
   base::TimeDelta last_frame_timestamp_;