even third_party/speex/speex.h is wrapper to system speex, here are some
includes included directly from third party dir...

--- chromium-browser-23.0.1271.64/src/remoting/codec/audio_decoder_speex.cc~	2012-10-31 19:01:20.000000000 +0000
+++ chromium-browser-23.0.1271.64/src/remoting/codec/audio_decoder_speex.cc	2012-11-12 23:04:42.083266707 +0000
@@ -11,9 +11,9 @@
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "remoting/proto/audio.pb.h"
-#include "third_party/speex/speex.h"
-#include "third_party/speex/include/speex/speex_callbacks.h"
-#include "third_party/speex/include/speex/speex_stereo.h"
+#include <speex/speex.h>
+#include <speex/speex_callbacks.h>
+#include <speex/speex_stereo.h>
 
 namespace remoting {
 
--- chromium-browser-23.0.1271.64/src/remoting/codec/audio_encoder_speex.cc~	2012-10-31 19:01:20.000000000 +0000
+++ chromium-browser-23.0.1271.64/src/remoting/codec/audio_encoder_speex.cc	2012-11-12 23:06:33.544849553 +0000
@@ -11,8 +11,8 @@
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "remoting/proto/audio.pb.h"
-#include "third_party/speex/speex.h"
-#include "third_party/speex/include/speex/speex_stereo.h"
+#include <speex/speex.h>
+#include <speex/speex_stereo.h>
 
 namespace {
 // A quality of 8 in wide band mode corresponds to 27,800 bits per second.