[Cronet] Change interface APIs to abstract classes

components/cronet/android/java/src/org/chromium/net/StatusListener.java

Index: components/cronet/android/java/src/org/chromium/net/StatusListener.java
diff --git a/components/cronet/android/java/src/org/chromium/net/StatusListener.java b/components/cronet/android/java/src/org/chromium/net/StatusListener.java
index a20c23445e70f40d99561af0fa2cdca3cb144189..6f014c84c8bececac36258af706ad7ec1f2b0cf9 100644
--- a/components/cronet/android/java/src/org/chromium/net/StatusListener.java
+++ b/components/cronet/android/java/src/org/chromium/net/StatusListener.java
@@ -5,14 +5,14 @@
 package org.chromium.net;
 
 /**
- * Listener interface for receiving the status information of a request.
+ * Listener class for receiving the status information of a request.
  */
-public interface StatusListener {
+public abstract class StatusListener {
     /**
      * Called on {@link UrlRequest}'s {@link java.util.concurrent.Executor}'s
      * thread when request status is obtained.
      * @param status integer representing the status of the request. It is
      *         one of the values defined in {@link RequestStatus}.
      */
-    public void onStatus(int status);
+    public abstract void onStatus(int status);
 }