Revert of Break peerconnection_jni.cc into multiple files, in "pc" directory.

webrtc/sdk/android/src/jni/pc/datachannelobserver_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_DATACHANNELOBSERVER_JNI_H_
-#define WEBRTC_SDK_ANDROID_SRC_JNI_PC_DATACHANNELOBSERVER_JNI_H_
-
-#include "webrtc/api/datachannelinterface.h"
-#include "webrtc/sdk/android/src/jni/jni_helpers.h"
-
-namespace webrtc_jni {
-
-// Adapter for a Java DataChannel$Observer presenting a C++ DataChannelObserver
-// and dispatching the callback from C++ back to Java.
-class DataChannelObserverJni : public webrtc::DataChannelObserver {
- public:
-  DataChannelObserverJni(JNIEnv* jni, jobject j_observer);
-  virtual ~DataChannelObserverJni() {}
-
-  void OnBufferedAmountChange(uint64_t previous_amount) override;
-  void OnStateChange() override;
-  void OnMessage(const webrtc::DataBuffer& buffer) override;
-
- private:
-  const ScopedGlobalRef<jobject> j_observer_global_;
-  const ScopedGlobalRef<jclass> j_observer_class_;
-  const ScopedGlobalRef<jclass> j_buffer_class_;
-  const jmethodID j_on_buffered_amount_change_mid_;
-  const jmethodID j_on_state_change_mid_;
-  const jmethodID j_on_message_mid_;
-  const jmethodID j_buffer_ctor_;
-};
-
-}  // namespace webrtc_jni
-
-#endif  // WEBRTC_SDK_ANDROID_SRC_JNI_PC_DATACHANNELOBSERVER_JNI_H_