[Remoting Android] Refactor OAuth Token Fetching Code

remoting/android/java/src/org/chromium/chromoting/HostListManager.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.chromoting;
 
 import android.os.Handler;
 import android.os.HandlerThread;
 import android.os.Looper;
 
@@ skipping 257 matching lines @@
                 byte[] requestBytes = requestBody.getBytes("UTF-8");
                 OutputStream outStream = link.getOutputStream();
                 outStream.write(requestBytes);
                 outStream.close();
             }
 
             // Listen for the server to respond.
             int status = link.getResponseCode();
             switch (status) {
                 case HttpURLConnection.HTTP_OK:  // 200
+                case HttpURLConnection.HTTP_NO_CONTENT:  // 204

[Yuwei, 2016/05/13 00:30:17]

This is a quick fix for the HostListManager. Turns out the server will respond
to the delete operation with 204 status code.

[Lambros, 2016/05/13 01:11:31]

We should probably replace this switch-statement with testing ranges of HTTP
codes.
200-299 are all OK, 400-499 are AUTH_FAILED, 500-599 are SERVICE_UNAVAILABLE,
everything else is UNKNOWN.

We've had problems in the past where the server returned a different code than
expected, so now might be a good time to make this change?

Doesn't need to hold up this CL if you want to do it separately.

[Yuwei, 2016/05/13 03:53:58]

Sure. I'll add a TODO here. BTW I think only 401 is for AUTH_FAILED. 4XX can be
not found and incorrect request, etc...

                     break;
                 case HttpURLConnection.HTTP_UNAUTHORIZED:  // 401
                     error = Error.AUTH_FAILED;
                     break;
                 case HttpURLConnection.HTTP_BAD_GATEWAY:  // 502
                 case HttpURLConnection.HTTP_UNAVAILABLE:  // 503
                     error = Error.SERVICE_UNAVAILABLE;
                     break;
                 default:
                     error = Error.UNKNOWN;
@@ skipping 15 matching lines @@
             throw new RuntimeException("Unexpected error while fetching host list: ", ex);
         } catch (IOException ex) {
             return new Response(Error.NETWORK_ERROR, null);
         } finally {
             if (link != null) {
                 link.disconnect();
             }
         }
     }
 }