Make decoder_model_info match the spec better.

Rename the following struct members and function to match their names in
the spec:
  buffer_removal_delay_present => buffer_removal_time_present
  buffer_removal_delay => buffer_removal_time
  tu_presentation_delay => frame_presentation_time
  frame_presentation_delay_length => frame_presentation_time_length
  av1_read_tu_pts_info => av1_read_temporal_point_info

Declare the frame_presentation_time member of struct AV1Common as
uint32_t because it is at most 32 bits long. For the same reason,
declare the buffer_removal_time member of struct aom_op_timing_info_t as
uint32_t. This allows us to remove the uint32_t casts on these members
when we pass them to aom_wb_write_unsigned_literal(). Add checks to
ensure the values of these members do not overflow uint32_t.

Remove the unused tu_presentation_delay_flag member of struct AV1Common.

Change-Id: Id50dd3dd2892d1a9a99b7d469c244a99141e19e7
diff --git a/av1/common/timing.h b/av1/common/timing.h
index 2562951..1749baa 100644
--- a/av1/common/timing.h
+++ b/av1/common/timing.h
@@ -27,8 +27,8 @@
 typedef struct aom_dec_model_info {
   uint32_t num_units_in_decoding_tick;
   int encoder_decoder_buffer_delay_length;
-  int buffer_removal_delay_length;
-  int frame_presentation_delay_length;
+  int buffer_removal_time_length;
+  int frame_presentation_time_length;
 } aom_dec_model_info_t;
 
 typedef struct aom_dec_model_op_parameters {
@@ -43,7 +43,7 @@
 } aom_dec_model_op_parameters_t;
 
 typedef struct aom_op_timing_info_t {
-  int64_t buffer_removal_delay;
+  uint32_t buffer_removal_time;
 } aom_op_timing_info_t;
 
 void set_aom_dec_model_info(aom_dec_model_info_t *decoder_model);