fix build

src/core/ext/filters/channel_idle/legacy_channel_idle_filter.cc

@@ -58,12 +58,7 @@ namespace grpc_core {
 
 namespace {
 
-// TODO(roth): This can go back to being a constant when the experiment
-// is removed.
-Duration DefaultIdleTimeout() {
-  if (IsClientIdlenessEnabled()) return Duration::Minutes(30);
-  return Duration::Infinity();
-}
+constexpr Duration kDefaultIdleTimeout = Duration::Minutes(30);
 
 // If these settings change, make sure that we are not sending a GOAWAY for
 // inproc transport, since a GOAWAY to inproc ends up destroying the transport.
@@ -86,7 +81,7 @@ namespace {
 
 Duration GetClientIdleTimeout(const ChannelArgs& args) {
   return args.GetDurationFromIntMillis(GRPC_ARG_CLIENT_IDLE_TIMEOUT_MS)
-      .value_or(DefaultIdleTimeout());
+      .value_or(kDefaultIdleTimeout);
 }
 
 }  // namespace