UMA log for audio_device Init and Start(Playout|Recording). Make Init return a more specific error …

webrtc/modules/audio_device/audio_device_generic.h

 /*
  *  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.
  */
 
 #ifndef WEBRTC_AUDIO_DEVICE_AUDIO_DEVICE_GENERIC_H
 #define WEBRTC_AUDIO_DEVICE_AUDIO_DEVICE_GENERIC_H
 
 #include "webrtc/modules/audio_device/audio_device_buffer.h"
 #include "webrtc/modules/audio_device/include/audio_device.h"
 
 namespace webrtc {
 
 class AudioDeviceGeneric {
  public:
+  // For use with UMA logging. Must be kept in sync with chromiums

[henrika_webrtc, 2016/06/30 08:44:20]

..."with histograms.xml in Chrome"

[Max Morin WebRTC, 2016/06/30 10:56:04]

Done.

+  // histograms.xml.
+  enum class InitStatus {
+    kOk = 0,

[henrika_webrtc, 2016/06/30 08:44:20]

don't we use the Google C++ code style? 
Like: OK, PLAYOUT_ERROR etc.

[Max Morin WebRTC, 2016/06/30 10:56:04]

Done.

+    kPlayoutError = 1,
+    kRecordingError = 2,
+    kOtherError = 3,
+    kNumStatuses = 4
+  };
   // Retrieve the currently utilized audio layer
   virtual int32_t ActiveAudioLayer(
       AudioDeviceModule::AudioLayer& audioLayer) const = 0;
 
   // Main initializaton and termination
-  virtual int32_t Init() = 0;
+  virtual InitStatus Init() = 0;
   virtual int32_t Terminate() = 0;
   virtual bool Initialized() const = 0;
 
   // Device enumeration
   virtual int16_t PlayoutDevices() = 0;
   virtual int16_t RecordingDevices() = 0;
   virtual int32_t PlayoutDeviceName(uint16_t index,
                                     char name[kAdmMaxDeviceNameSize],
                                     char guid[kAdmMaxGuidSize]) = 0;
   virtual int32_t RecordingDeviceName(uint16_t index,
@@ skipping 135 matching lines @@
   virtual void ClearRecordingError() = 0;
 
   virtual void AttachAudioBuffer(AudioDeviceBuffer* audioBuffer) = 0;
 
   virtual ~AudioDeviceGeneric() {}
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_AUDIO_DEVICE_AUDIO_DEVICE_GENERIC_H