Injectable logging

Allows passing a Loggable to PCFactory.initializationOptions, which
is then injected to Logging.java and logging.h. Future log messages
in both Java and native will then be passed to this Loggable.

Bug: webrtc:9225
Change-Id: I2ff693380639448301a78a93dc11d3a0106f0967
Reviewed-on: https://webrtc-review.googlesource.com/73243
Commit-Queue: Paulina Hensman <phensman@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23241}

sdk/android/src/java/org/webrtc/JNILogging.java

@@ -0,0 +1,28 @@
+/*
+ *  Copyright 2018 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.
+ */
+
+package org.webrtc;
+
+import org.webrtc.CalledByNative;
+import org.webrtc.Loggable;
+import org.webrtc.Logging.Severity;
+
+class JNILogging {
+  private final Loggable loggable;
+
+  public JNILogging(Loggable loggable) {
+    this.loggable = loggable;
+  }
+
+  @CalledByNative
+  public void logToInjectable(String message, Integer severity, String tag) {
+    loggable.onLogMessage(message, Severity.values()[severity], tag);
+  }
+}