Fix include guards
diff --git a/src/core/lib/channel/channel_stack.h b/src/core/lib/channel/channel_stack.h
index 52362f0..d91a65c 100644
--- a/src/core/lib/channel/channel_stack.h
+++ b/src/core/lib/channel/channel_stack.h
@@ -31,8 +31,8 @@
  *
  */
 
-#ifndef GRPC_CORE_CHANNEL_CHANNEL_STACK_H
-#define GRPC_CORE_CHANNEL_CHANNEL_STACK_H
+#ifndef GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_H
+#define GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_H
 
 /* A channel filter defines how operations on a channel are implemented.
    Channel filters are chained together to create full channels, and if those
@@ -257,4 +257,4 @@
 #define GRPC_CALL_LOG_OP(sev, elem, op) \
   if (grpc_trace_channel) grpc_call_log_op(sev, elem, op)
 
-#endif /* GRPC_CORE_CHANNEL_CHANNEL_STACK_H */
+#endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_H */