Improves stereo/mono audio support on Android

webrtc/modules/audio_device/android/audio_device_template.h

 /*
  *  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.
  */
 
@@ skipping 313 matching lines @@
   int32_t SetMicrophoneMute(bool enable) override {
     FATAL() << "Not implemented";
     return -1;
   }
 
   int32_t MicrophoneMute(bool& enabled) const override {
     FATAL() << "Not implemented";
     return -1;
   }
 
+  // Returns true if the audio manager has been configured to support stereo
+  // and false otherwised. Default is mono.
   int32_t StereoPlayoutIsAvailable(bool& available) override {
     LOG(INFO) << __FUNCTION__;
-    available = false;
+    available = audio_manager_->IsStereoPlayoutSupported();
     return 0;
   }
 
-  // TODO(henrika): add support.
   int32_t SetStereoPlayout(bool enable) override {
     LOG(INFO) << __FUNCTION__;
-    // Allow disabling stereo playout, as that matches returning false(0) from
-    // StereoPlayoutIsAvailable and is the default case.
-    return enable ? -1 : 0;
+    bool available = audio_manager_->IsStereoPlayoutSupported();
+    // Android does not support changes between mono and stero on the fly.
+    // Instead, the native audio layer is configured via the audio manager
+    // to either support mono or stereo. It is allowed to call this method
+    // if that same state is not modified.
+    return (enable == available) ? 0 : -1;
   }
 
-  // TODO(henrika): add support.
   int32_t StereoPlayout(bool& enabled) const override {
-    enabled = false;
-    FATAL() << "Should never be called";
-    return -1;
+    enabled = audio_manager_->IsStereoPlayoutSupported();
+    return 0;
   }
 
   int32_t StereoRecordingIsAvailable(bool& available) override {
     LOG(INFO) << __FUNCTION__;
-    available = false;
+    available = audio_manager_->IsStereoRecordSupported();
     return 0;
   }
 
   int32_t SetStereoRecording(bool enable) override {
     LOG(INFO) << __FUNCTION__;
-    return -1;
+    bool available = audio_manager_->IsStereoRecordSupported();
+    // Android does not support changes between mono and stero on the fly.
+    // Instead, the native audio layer is configured via the audio manager
+    // to either support mono or stereo. It is allowed to call this method
+    // if that same state is not modified.
+    return (enable == available) ? 0 : -1;
   }
 
   int32_t StereoRecording(bool& enabled) const override {
     LOG(INFO) << __FUNCTION__;
-    enabled = false;
+    enabled = audio_manager_->IsStereoRecordSupported();
     return 0;
   }
 
   int32_t PlayoutDelay(uint16_t& delay_ms) const override {
     // Best guess we can do is to use half of the estimated total delay.
     delay_ms = audio_manager_->GetDelayEstimateInMilliseconds() / 2;
     RTC_DCHECK_GT(delay_ms, 0);
     return 0;
   }
 
@@ skipping 123 matching lines @@
   OutputType output_;
 
   InputType input_;
 
   bool initialized_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_DEVICE_ANDROID_AUDIO_DEVICE_TEMPLATE_H_