Revert arena size fix

src/core/lib/surface/call.cc

@@ -67,9 +67,6 @@
 
 #define MAX_SEND_EXTRA_METADATA_COUNT 3
 
-// Used to create arena for the first call.
-#define ESTIMATED_MDELEM_COUNT 16
-
 /* Status data for a request can come from several sources; this
    enumerates them all, and acts as a priority sorting for which
    status to return to the application - earlier entries override
@@ -326,11 +323,6 @@ static parent_call* get_parent_call(grpc_call* call) {
   return (parent_call*)gpr_atm_acq_load(&call->parent_call_atm);
 }
 
-size_t grpc_call_get_initial_size_estimate() {
-  return sizeof(grpc_call) + sizeof(batch_control) * MAX_CONCURRENT_BATCHES +
-         sizeof(grpc_linked_mdelem) * ESTIMATED_MDELEM_COUNT;
-}
-
 grpc_error* grpc_call_create(const grpc_call_create_args* args,
                              grpc_call** out_call) {
   GPR_TIMER_SCOPE("grpc_call_create", 0);

src/core/lib/surface/call.h

@@ -98,11 +98,6 @@ void* grpc_call_context_get(grpc_call* call, grpc_context_index elem);
 
 uint8_t grpc_call_is_client(grpc_call* call);
 
-/* Get the estimated memory size for a call BESIDES the call stack. Combined
- * with the size of the call stack, it helps estimate the arena size for the
- * initial call. */
-size_t grpc_call_get_initial_size_estimate();
-
 /* Return an appropriate compression algorithm for the requested compression \a
  * level in the context of \a call. */
 grpc_compression_algorithm grpc_call_compression_for_level(

src/core/lib/surface/channel.cc

@@ -108,8 +108,7 @@ grpc_channel* grpc_channel_create_with_builder(
 
   gpr_atm_no_barrier_store(
       &channel->call_size_estimate,
-      (gpr_atm)CHANNEL_STACK_FROM_CHANNEL(channel)->call_stack_size +
-          grpc_call_get_initial_size_estimate());
+      (gpr_atm)CHANNEL_STACK_FROM_CHANNEL(channel)->call_stack_size);
 
   grpc_compression_options_init(&channel->compression_options);
   for (size_t i = 0; i < args->num_args; i++) {