[Cronet] Add error code and immediatelyRetryable() to UrlRequestException

components/cronet/android/url_request_error.h

+// Copyright 2016 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.
+
+#ifndef COMPONENTS_CRONET_ANDROID_URL_REQUEST_ERROR_H_
+#define COMPONENTS_CRONET_ANDROID_URL_REQUEST_ERROR_H_
+
+namespace cronet {
+
+// Error codes for the most popular network stack error codes.
+// For descriptions see corresponding constants in UrlRequestException.java.
+// A Java counterpart will be generated for this enum.
+// GENERATED_JAVA_ENUM_PACKAGE: org.chromium.net
+enum UrlRequestError {

[xunjieli, 2016/04/23 10:37:15]

It turns out that there is already a java class with all NetError codes as
static ints
(https://code.google.com/p/chromium/codesearch#search/&q=NetError%20file:java$...).
Andrei told me about it.
We should probably get rid of this and do the mapping and retryable logic
entirely Java side. WDYT?

[pauljensen, 2016/04/29 14:39:05]

I don't see a benefit to doing it Java-side.  I think there may actually be
benefits to doing it native side:
1. native code may be smaller, and is certainly faster
2. UrlRequestException is in the API side, rather than the implementation side,
and it may be much harder to make changes in the API side, e.g. if the
implementation side is auto-updated but the API side is linked into an app.

+  LISTENER_EXCEPTION_THROWN,
+  HOSTNAME_NOT_RESOLVED,
+  INTERNET_DISCONNECTED,
+  NETWORK_CHANGED,
+  TIMED_OUT,
+  CONNECTION_CLOSED,
+  CONNECTION_TIMED_OUT,
+  CONNECTION_REFUSED,
+  CONNECTION_RESET,
+  ADDRESS_UNREACHABLE,
+  OTHER,
+};
+
+// Converts most popular net::ERR_* values to counterparts accessible in Java.
+UrlRequestError NetErrorToUrlRequestError(int net_error);
+
+}  // namespace cronet
+
+#endif  // COMPONENTS_CRONET_ANDROID_URL_REQUEST_ERROR_H_