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/modules/audio_processing/agc/agc_manager_direct.h

@@ -0,0 +1,108 @@
+/*
+ *  Copyright (c) 2013 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.
+ */
+
+#ifndef WEBRTC_MODULES_AUDIO_PROCESSING_AGC_AGC_MANAGER_DIRECT_H_
+#define WEBRTC_MODULES_AUDIO_PROCESSING_AGC_AGC_MANAGER_DIRECT_H_
+
+#include "webrtc/base/scoped_ptr.h"
+#include "webrtc/modules/audio_processing/agc/agc.h"
+
+namespace webrtc {
+
+class AudioFrame;
+class DebugFile;
+class GainControl;
+
+// Callbacks that need to be injected into AgcManagerDirect to read and control
+// the volume values. This is done to remove the VoiceEngine dependency in
+// AgcManagerDirect.
+// TODO(aluebs): Remove VolumeCallbacks.
+class VolumeCallbacks {
+ public:
+  virtual ~VolumeCallbacks() {}
+  virtual void SetMicVolume(int volume) = 0;
+  virtual int GetMicVolume() = 0;
+};
+
+// Direct interface to use AGC to set volume and compression values.
+// AudioProcessing uses this interface directly to integrate the callback-less
+// AGC.
+//
+// This class is not thread-safe.
+class AgcManagerDirect final {
+ public:
+  // AgcManagerDirect will configure GainControl internally. The user is
+  // responsible for processing the audio using it after the call to Process.
+  // The operating range of startup_min_level is [12, 255] and any input value
+  // outside that range will be clamped.
+  AgcManagerDirect(GainControl* gctrl,
+                   VolumeCallbacks* volume_callbacks,
+                   int startup_min_level);
+  // Dependency injection for testing. Don't delete |agc| as the memory is owned
+  // by the manager.
+  AgcManagerDirect(Agc* agc,
+                   GainControl* gctrl,
+                   VolumeCallbacks* volume_callbacks,
+                   int startup_min_level);
+  ~AgcManagerDirect();
+
+  int Initialize();
+  void AnalyzePreProcess(int16_t* audio,
+                         int num_channels,
+                         size_t samples_per_channel);
+  void Process(const int16_t* audio, size_t length, int sample_rate_hz);
+
+  // Call when the capture stream has been muted/unmuted. This causes the
+  // manager to disregard all incoming audio; chances are good it's background
+  // noise to which we'd like to avoid adapting.
+  void SetCaptureMuted(bool muted);
+  bool capture_muted() { return capture_muted_; }
+
+  float voice_probability();
+
+ private:
+  // Sets a new microphone level, after first checking that it hasn't been
+  // updated by the user, in which case no action is taken.
+  void SetLevel(int new_level);
+
+  // Set the maximum level the AGC is allowed to apply. Also updates the
+  // maximum compression gain to compensate. The level must be at least
+  // |kClippedLevelMin|.
+  void SetMaxLevel(int level);
+
+  int CheckVolumeAndReset();
+  void UpdateGain();
+  void UpdateCompressor();
+
+  rtc::scoped_ptr<Agc> agc_;
+  GainControl* gctrl_;
+  VolumeCallbacks* volume_callbacks_;
+
+  int frames_since_clipped_;
+  int level_;
+  int max_level_;
+  int max_compression_gain_;
+  int target_compression_;
+  int compression_;
+  float compression_accumulator_;
+  bool capture_muted_;
+  bool check_volume_on_next_process_;
+  bool startup_;
+  int startup_min_level_;
+
+  rtc::scoped_ptr<DebugFile> file_preproc_;
+  rtc::scoped_ptr<DebugFile> file_postproc_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(AgcManagerDirect);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_AUDIO_PROCESSING_AGC_AGC_MANAGER_DIRECT_H_