Relanding: Break peerconnection_jni.cc into multiple files, in "pc" directory.

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

 /*
  *  Copyright 2015 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 13 matching lines @@
 
 // LoadGlobalClassReferenceHolder must be called in JNI_OnLoad.
 void LoadGlobalClassReferenceHolder();
 // FreeGlobalClassReferenceHolder must be called in JNI_UnLoad.
 void FreeGlobalClassReferenceHolder();
 
 // Returns a global reference guaranteed to be valid for the lifetime of the
 // process.
 jclass FindClass(JNIEnv* jni, const char* name);
 
-// Convenience macro defining JNI-accessible methods in the org.webrtc package.
-// Eliminates unnecessary boilerplate and line-wraps, reducing visual clutter.
-#define JOW(rettype, name) \
-  extern "C" JNIEXPORT rettype JNICALL Java_org_webrtc_##name
-
 }  // namespace webrtc_jni
 
 #endif  // WEBRTC_SDK_ANDROID_SRC_JNI_CLASSREFERENCEHOLDER_H_