Support building WebRTC without audio and video for Android

webrtc/sdk/android/src/jni/audio_jni.h

+/*
+ *  Copyright 2017 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_SDK_ANDROID_SRC_JNI_AUDIO_JNI_H_
+#define WEBRTC_SDK_ANDROID_SRC_JNI_AUDIO_JNI_H_
+
+// Adding 'nogncheck' to disable the gn include headers check.
+// We don't want this target depend on audio related targets
+#include "webrtc/api/audio_codecs/audio_decoder_factory.h"  // nogncheck
+#include "webrtc/api/audio_codecs/audio_encoder_factory.h"  // nogncheck
+#include "webrtc/base/scoped_ref_ptr.h"
+
+namespace webrtc_jni {
+
+rtc::scoped_refptr<webrtc::AudioDecoderFactory> CreateAudioDecoderFactory();
+
+rtc::scoped_refptr<webrtc::AudioEncoderFactory> CreateAudioEncoderFactory();
+
+}  // namespace webrtc_jni
+
+#endif  // WEBRTC_SDK_ANDROID_SRC_JNI_AUDIO_JNI_H_