Migrate bitwriter to the interface in aom/master

Change-Id: I73d46229f0feea43cbe933e51da997833cce032b
diff --git a/av1/encoder/bitstream.c b/av1/encoder/bitstream.c
index fedc263..82f60fa 100644
--- a/av1/encoder/bitstream.c
+++ b/av1/encoder/bitstream.c
@@ -2890,7 +2890,7 @@
   const int have_tiles = tile_cols * tile_rows > 1;
 #endif  // CONFIG_EXT_TILE
 #if CONFIG_ANS
-  BufAnsCoder *buf_ans = &cpi->buf_ans;
+  struct BufAnsCoder *buf_ans = &cpi->buf_ans;
 #endif  // CONFIG_ANS
 
   *max_tile_size = 0;
diff --git a/av1/encoder/bitwriter.h b/av1/encoder/bitwriter.h
index e4e7250..21cc6a3 100644
--- a/av1/encoder/bitwriter.h
+++ b/av1/encoder/bitwriter.h
@@ -14,25 +14,6 @@
 #ifndef AOM10_ENCODER_BITWRITER_H_
 #define AOM10_ENCODER_BITWRITER_H_
 
-#include "./aom_config.h"
-#include "aom_dsp/prob.h"
-// Include bitwriter.h in the CONFIG_ANS to keep ANS building while
-// porting from VP10 style entropy coder abstraction to the aom/master style
-// entropy coder abstractions.
 #include "aom_dsp/bitwriter.h"
 
-#if CONFIG_ANS
-typedef struct BufAnsCoder BufAnsCoder;
-#include "aom_dsp/buf_ans.h"
-#define aom_writer BufAnsCoder
-#define aom_write buf_uabs_write
-#define aom_write_bit buf_uabs_write_bit
-#define aom_write_literal buf_uabs_write_literal
-#else
-#define aom_writer aom_writer
-#define aom_write aom_write
-#define aom_write_bit aom_write_bit
-#define aom_write_literal aom_write_literal
-#endif
-
 #endif  // AOM10_ENCODER_BITWRITER_H_
diff --git a/av1/encoder/treewriter.h b/av1/encoder/treewriter.h
index 7a5c702..eb7f0a7 100644
--- a/av1/encoder/treewriter.h
+++ b/av1/encoder/treewriter.h
@@ -13,9 +13,9 @@
 #define AV1_ENCODER_TREEWRITER_H_
 
 #ifdef AV1_FORCE_AOMBOOL_TREEWRITER
-#include "aom_dsp/bitwriter.h"
-#define tree_writer aom_writer
-#define tree_bit_write aom_write
+#include "aom_dsp/dkboolwriter.h"
+#define tree_writer aom_dk_writer
+#define tree_bit_write aom_dk_write
 #else
 #include "av1/encoder/bitwriter.h"
 #define tree_writer aom_writer