TurnCustomizer - an interface for modifying stun messages sent by TurnPort

This patch adds an interface that allows modification of stun messages
sent by TurnPort. A user can inject a TurnCustomizer on the RTCConfig
and the TurnCustomizer will be invoked by TurnPort before sending
message. This allows user to e.g add custom attributes as described
in rtf5389.

BUG=webrtc:8313

Change-Id: I6f4333e9f8ff7fd20f32677be19285f15e1180b6
Reviewed-on: https://webrtc-review.googlesource.com/7618
Reviewed-by: Guido Urdaneta <guidou@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Commit-Queue: Jonas Oreland <jonaso@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20233}

sdk/android/src/jni/pc/java_native_conversion.cc

@@ -478,6 +478,15 @@ void JavaToNativeRTCConfiguration(
   jmethodID get_max_id =
       GetMethodID(jni, j_interval_range_class, "getMax", "()I");
 
+  jfieldID j_turn_customizer_type_id = GetFieldID(
+      jni, j_rtc_config_class, "turnCustomizer", "Lorg/webrtc/TurnCustomizer;");
+  jobject j_turn_customizer =
+      GetNullableObjectField(jni, j_rtc_config, j_turn_customizer_type_id);
+
+  jclass j_turn_customizer_class = jni->FindClass("org/webrtc/TurnCustomizer");
+  jfieldID j_native_turn_customizer_id =
+      GetFieldID(jni, j_turn_customizer_class, "nativeTurnCustomizer", "J");
+
   rtc_config->type = JavaToNativeIceTransportsType(jni, j_ice_transports_type);
   rtc_config->bundle_policy = JavaToNativeBundlePolicy(jni, j_bundle_policy);
   rtc_config->rtcp_mux_policy =
@@ -522,6 +531,11 @@ void JavaToNativeRTCConfiguration(
     int max = jni->CallIntMethod(j_ice_regather_interval_range, get_max_id);
     rtc_config->ice_regather_interval_range.emplace(min, max);
   }
+
+  if (!IsNull(jni, j_turn_customizer)) {
+    rtc_config->turn_customizer = reinterpret_cast<webrtc::TurnCustomizer*>(
+        GetLongField(jni, j_turn_customizer, j_native_turn_customizer_id));
+  }
 }
 
 void JavaToNativeRtpParameters(JNIEnv* jni,

sdk/android/src/jni/pc/turncustomizer_jni.cc

@@ -0,0 +1,26 @@
+/*
+ *  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.
+ */
+
+#include "api/turncustomizer.h"
+#include "sdk/android/src/jni/jni_helpers.h"
+
+namespace webrtc {
+namespace jni {
+
+JNI_FUNCTION_DECLARATION(void,
+                         TurnCustomizer_nativeFreeTurnCustomizer,
+                         JNIEnv* jni,
+                         jclass,
+                         jlong j_turn_customizer_pointer) {
+  delete reinterpret_cast<TurnCustomizer*>(j_turn_customizer_pointer);
+}
+
+}  // namespace jni
+}  // namespace webrtc