Add new Cronet exception class for QUIC errors

components/cronet/android/api/src/org/chromium/net/UrlRequestException.java

Index: components/cronet/android/api/src/org/chromium/net/UrlRequestException.java
diff --git a/components/cronet/android/api/src/org/chromium/net/UrlRequestException.java b/components/cronet/android/api/src/org/chromium/net/UrlRequestException.java
index 92201aa32471128ce721a81cab80fbf8b061f73b..f1ab73877501e30d4e8213924be7808926c9da08 100644
--- a/components/cronet/android/api/src/org/chromium/net/UrlRequestException.java
+++ b/components/cronet/android/api/src/org/chromium/net/UrlRequestException.java
@@ -14,7 +14,9 @@ import java.io.IOException;
  *     {@link #getErrorCode} will return {@link #ERROR_LISTENER_EXCEPTION_THROWN}.
  * <li>Cronet fails to process a network request. In this case
  *     {@link #getErrorCode} and {@link #getCronetInternalErrorCode} can be used to get more
- *     information about the specific type of failure.
+ *     information about the specific type of failure. If {@link #getCronetInternalErrorCode}
+ *     returns QUIC_PROTOCOL_ERROR, this exception can be cast to a {@link QuicException}

[pauljensen, 2016/06/30 17:35:12]

It's quite awkward to reference a value here without an easy way of knowing how
to use that value. (users would have to know to click the
getCronetInternalErrorCode link and then click the link to the errors and then
grep for QUIC_PROTOCOL_ERROR and then define their own constant in Java for this
value)  I'd propose adding ERROR_QUIC_PROTOCOL_FAILED to this class.

[mgersh, 2016/06/30 22:55:53]

Done. (Was the different name just to avoid saying "ERROR" twice?)

+ *     which can provide further details.
  * </ul>
  */
 public class UrlRequestException extends IOException {