Fix missing libc++ includes in webrtc

Several files refer to symbols declared in headers not explicitly
included. This compiles now because libc++ tranitively includes these
headers via other libc++ headers; however, these transitive includes are
not guaranteed to exist and in Chrome, will no longer exist once libc++
is compiled with modules.

Bug: chromium:543704
Change-Id: I638bb02df3d050a48345248e80aebd2dd60956c1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/295762
Auto-Submit: Alan Zhao <ayzhao@google.com>
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39448}
diff --git a/api/make_ref_counted.h b/api/make_ref_counted.h
index cc88717..e958da9 100644
--- a/api/make_ref_counted.h
+++ b/api/make_ref_counted.h
@@ -10,6 +10,7 @@
 #ifndef API_MAKE_REF_COUNTED_H_
 #define API_MAKE_REF_COUNTED_H_
 
+#include <type_traits>
 #include <utility>
 
 #include "rtc_base/ref_counted_object.h"
diff --git a/modules/audio_processing/transient/wpd_node.h b/modules/audio_processing/transient/wpd_node.h
index 41614fa..645bc5f 100644
--- a/modules/audio_processing/transient/wpd_node.h
+++ b/modules/audio_processing/transient/wpd_node.h
@@ -11,6 +11,7 @@
 #ifndef MODULES_AUDIO_PROCESSING_TRANSIENT_WPD_NODE_H_
 #define MODULES_AUDIO_PROCESSING_TRANSIENT_WPD_NODE_H_
 
+#include <cstddef>
 #include <memory>
 
 namespace webrtc {