Update audio_processing module

Corresponds to upstream commit 524e9b043e7e86fd72353b987c9d5f6a1ebf83e1

Update notes:

 * Pull in third party license file

 * Replace .gypi files with BUILD.gn to keep track of what changes
   upstream

 * Bunch of new filse pulled in as dependencies

 * Won't build yet due to changes needed on top of these

webrtc/system_wrappers/source/sleep.cc

@@ -0,0 +1,36 @@
+/*
+ *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+// An OS-independent sleep function.
+
+#include "webrtc/system_wrappers/interface/sleep.h"
+
+#ifdef _WIN32
+// For Sleep()
+#include <windows.h>
+#else
+// For nanosleep()
+#include <time.h>
+#endif
+
+namespace webrtc {
+
+void SleepMs(int msecs) {
+#ifdef _WIN32
+  Sleep(msecs);
+#else
+  struct timespec short_wait;
+  struct timespec remainder;
+  short_wait.tv_sec = msecs / 1000;
+  short_wait.tv_nsec = (msecs % 1000) * 1000 * 1000;
+  nanosleep(&short_wait, &remainder);
+#endif
+}
+
+}  // namespace webrtc