Added namespaces in the newly C++ified AEC code

webrtc/modules/audio_processing/aec/echo_cancellation_internal.h

Index: webrtc/modules/audio_processing/aec/echo_cancellation_internal.h
diff --git a/webrtc/modules/audio_processing/aec/echo_cancellation_internal.h b/webrtc/modules/audio_processing/aec/echo_cancellation_internal.h
index ccedb28a145702cc554c72ab5b3696584f5f4695..b4a6fd8390e6893c99e0a9ce5ec969868b18342b 100644
--- a/webrtc/modules/audio_processing/aec/echo_cancellation_internal.h
+++ b/webrtc/modules/audio_processing/aec/echo_cancellation_internal.h
@@ -16,6 +16,8 @@ extern "C" {
 }
 #include "webrtc/modules/audio_processing/aec/aec_core.h"
 
+namespace webrtc {
+
 typedef struct {
   int delayCtr;
   int sampFreq;
@@ -64,4 +66,6 @@ typedef struct {
   AecCore* aec;
 } Aec;
 
+}  // namespace webrtc
+
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AEC_ECHO_CANCELLATION_INTERNAL_H_