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

webrtc/sdk/android/src/jni/pc/mediaconstraints_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_VIDEO_JNI_H_
-#define WEBRTC_SDK_ANDROID_SRC_JNI_VIDEO_JNI_H_
+#ifndef WEBRTC_SDK_ANDROID_SRC_JNI_PC_MEDIACONSTRAINTS_JNI_H_
+#define WEBRTC_SDK_ANDROID_SRC_JNI_PC_MEDIACONSTRAINTS_JNI_H_
 
-#include <jni.h>
-
-#include "webrtc/rtc_base/scoped_ref_ptr.h"
-
-namespace cricket {
-class WebRtcVideoEncoderFactory;
-class WebRtcVideoDecoderFactory;
-}  // namespace cricket
+#include "webrtc/api/mediaconstraintsinterface.h"
+#include "webrtc/sdk/android/src/jni/jni_helpers.h"
 
 namespace webrtc_jni {
 
-class SurfaceTextureHelper;
+// Wrapper for a Java MediaConstraints object.  Copies all needed data so when
+// the constructor returns the Java object is no longer needed.
+class MediaConstraintsJni : public webrtc::MediaConstraintsInterface {
+ public:
+  MediaConstraintsJni(JNIEnv* jni, jobject j_constraints);
+  virtual ~MediaConstraintsJni() {}
 
-cricket::WebRtcVideoEncoderFactory* CreateVideoEncoderFactory(
-    JNIEnv* jni,
-    jobject j_encoder_factory);
+  // MediaConstraintsInterface.
+  const Constraints& GetMandatory() const override { return mandatory_; }
+  const Constraints& GetOptional() const override { return optional_; }
 
-cricket::WebRtcVideoDecoderFactory* CreateVideoDecoderFactory(
-    JNIEnv* jni,
-    jobject j_decoder_factory);
+ private:
+  // Helper for translating a List<Pair<String, String>> to a Constraints.
+  static void PopulateConstraintsFromJavaPairList(JNIEnv* jni,
+                                                  jobject j_constraints,
+                                                  const char* field_name,
+                                                  Constraints* field);
 
-jobject GetJavaSurfaceTextureHelper(
-    const rtc::scoped_refptr<SurfaceTextureHelper>& surface_texture_helper);
+  Constraints mandatory_;
+  Constraints optional_;
+};
 
 }  // namespace webrtc_jni
 
-#endif  // WEBRTC_SDK_ANDROID_SRC_JNI_VIDEO_JNI_H_
+#endif  // WEBRTC_SDK_ANDROID_SRC_JNI_PC_MEDIACONSTRAINTS_JNI_H_