Android: Replace webrtc_jni namespace with nested jni namespace

webrtc/sdk/android/src/jni/pc/rtpreceiverobserver_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_PC_RTPRECEIVEROBSERVER_JNI_H_
 #define WEBRTC_SDK_ANDROID_SRC_JNI_PC_RTPRECEIVEROBSERVER_JNI_H_
 
 #include "webrtc/api/rtpreceiverinterface.h"
 #include "webrtc/sdk/android/src/jni/jni_helpers.h"
 
-namespace webrtc_jni {
+namespace webrtc {
+namespace jni {
 
 // Adapter between the C++ RtpReceiverObserverInterface and the Java
 // RtpReceiver.Observer interface. Wraps an instance of the Java interface and
 // dispatches C++ callbacks to Java.
-class RtpReceiverObserverJni : public webrtc::RtpReceiverObserverInterface {
+class RtpReceiverObserverJni : public RtpReceiverObserverInterface {
  public:
   RtpReceiverObserverJni(JNIEnv* jni, jobject j_observer)
       : j_observer_global_(jni, j_observer) {}
 
   ~RtpReceiverObserverJni() override {}
 
   void OnFirstPacketReceived(cricket::MediaType media_type) override;
 
  private:
   const ScopedGlobalRef<jobject> j_observer_global_;
 };
 
-}  // namespace webrtc_jni
+}  // namespace jni
+}  // namespace webrtc
 
 #endif  // WEBRTC_SDK_ANDROID_SRC_JNI_PC_RTPRECEIVEROBSERVER_JNI_H_