Update common_audio

Corresponds to upstream commit 524e9b043e7e86fd72353b987c9d5f6a1ebf83e1

Update notes:

 * Moved src/ to webrtc/ to easily diff against the third_party/webrtc
   in the chromium tree

 * ARM/NEON/MIPS support is not yet hooked up

 * Tests have not been copied

webrtc/common_audio/vad/vad.cc

@@ -0,0 +1,63 @@
+/*
+ *  Copyright (c) 2014 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.
+ */
+
+#include "webrtc/common_audio/vad/include/vad.h"
+
+#include "webrtc/base/checks.h"
+
+namespace webrtc {
+
+namespace {
+
+class VadImpl final : public Vad {
+ public:
+  explicit VadImpl(Aggressiveness aggressiveness)
+      : handle_(nullptr), aggressiveness_(aggressiveness) {
+    Reset();
+  }
+
+  ~VadImpl() override { WebRtcVad_Free(handle_); }
+
+  Activity VoiceActivity(const int16_t* audio,
+                         size_t num_samples,
+                         int sample_rate_hz) override {
+    int ret = WebRtcVad_Process(handle_, sample_rate_hz, audio, num_samples);
+    switch (ret) {
+      case 0:
+        return kPassive;
+      case 1:
+        return kActive;
+      default:
+        RTC_DCHECK(false) << "WebRtcVad_Process returned an error.";
+        return kError;
+    }
+  }
+
+  void Reset() override {
+    if (handle_)
+      WebRtcVad_Free(handle_);
+    handle_ = WebRtcVad_Create();
+    RTC_CHECK(handle_);
+    RTC_CHECK_EQ(WebRtcVad_Init(handle_), 0);
+    RTC_CHECK_EQ(WebRtcVad_set_mode(handle_, aggressiveness_), 0);
+  }
+
+ private:
+  VadInst* handle_;
+  Aggressiveness aggressiveness_;
+};
+
+}  // namespace
+
+rtc::scoped_ptr<Vad> CreateVad(Vad::Aggressiveness aggressiveness) {
+  return rtc::scoped_ptr<Vad>(new VadImpl(aggressiveness));
+}
+
+}  // namespace webrtc