[Cronet] Do not call into native adapter after it is destroyed in ChromiumUrlRequest.java

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.net;
 
 import java.io.IOException;
 import java.nio.ByteBuffer;
 import java.nio.channels.ReadableByteChannel;
 import java.util.List;
@@ skipping 126 matching lines @@
     /**
      * Returns the HTTP status code. It may be 0 if the request has not started
      * or failed before getting the status code from the server. If the status
      * code is 206 (partial response) after {@link #setOffset} is called, the
      * method returns 200.
      */
     int getHttpStatusCode();
 
     /**
      * Returns the HTTP status text of the status line. For example, if the
-     * request has a "HTTP/1.1 200 OK" response, this method returns "OK".
+     * request has a "HTTP/1.1 200 OK" response, this method returns "OK". It
+     * returns null if the request has not started.
      */
     String getHttpStatusText();
 
     /**
      * Returns the response header value for the given name or {@code null} if
      * not found.
      */
     String getHeader(String name);
 
     /**
      * Returns an unmodifiable map of the response-header fields and values.
      * The null key is mapped to the HTTP status line for compatibility with
      * HttpUrlConnection.
      */
     Map<String, List<String>> getAllHeaders();
 
     /**
      * Returns the exception that occurred while executing the request of null
      * if the request was successful.
      */
     IOException getException();
 }