Add code for dummy file audio to fallback to dummy audio.

webrtc/modules/audio_device/audio_device_impl.cc

 /*
  *  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.
  */
 
@@ skipping 168 matching lines @@
 int32_t AudioDeviceModuleImpl::CreatePlatformSpecificObjects() {
   LOG(INFO) << __FUNCTION__;
 
   AudioDeviceGeneric* ptrAudioDevice(NULL);
 
 #if defined(WEBRTC_DUMMY_AUDIO_BUILD)
   ptrAudioDevice = new AudioDeviceDummy(Id());
   LOG(INFO) << "Dummy Audio APIs will be utilized";
 #elif defined(WEBRTC_DUMMY_FILE_DEVICES)
   ptrAudioDevice = FileAudioDeviceFactory::CreateFileAudioDevice(Id());
-  LOG(INFO) << "Will use file-playing dummy device.";
+  if (ptrAudioDevice) {
+    LOG(INFO) << "Will use file-playing dummy device.";
+  } else {
+    // Create a dummy device instead.
+    ptrAudioDevice = new AudioDeviceDummy(Id());
+    LOG(INFO) << "Dummy Audio APIs will be utilized";
+  }
 #else
   AudioLayer audioLayer(PlatformAudioLayer());
 
 // Create the *Windows* implementation of the Audio Device
 //
 #if defined(_WIN32)
   if ((audioLayer == kWindowsWaveAudio)
 #if !defined(WEBRTC_WINDOWS_CORE_AUDIO_BUILD)
       // Wave audio is default if Core audio is not supported in this build
       || (audioLayer == kPlatformDefaultAudio)
@@ skipping 1669 matching lines @@
 //  PlatformAudioLayer
 // ----------------------------------------------------------------------------
 
 AudioDeviceModule::AudioLayer AudioDeviceModuleImpl::PlatformAudioLayer()
     const {
   LOG(INFO) << __FUNCTION__;
   return _platformAudioLayer;
 }
 
 }  // namespace webrtc