Remove EXTRA_PROXY_INFO.

This has been deprecated since M because it very error-prone, and
there are documented replacements.

Test: m
Bug: 171872228
Change-Id: Ide9846a26fc440b3ec5b4e4b444a046e738de3d6
diff --git a/framework/src/android/net/ProxyInfo.java b/framework/src/android/net/ProxyInfo.java
index 745e20f..0deda37 100644
--- a/framework/src/android/net/ProxyInfo.java
+++ b/framework/src/android/net/ProxyInfo.java
@@ -37,8 +37,9 @@
  * Apache HTTP stack. So {@link URLConnection} and Apache's {@code HttpClient} will use
  * them automatically.
  *
- * Other HTTP stacks will need to obtain the proxy info from
- * {@link Proxy#PROXY_CHANGE_ACTION} broadcast as the extra {@link Proxy#EXTRA_PROXY_INFO}.
+ * Other HTTP stacks will need to obtain the proxy info by watching for the
+ * {@link Proxy#PROXY_CHANGE_ACTION} broadcast and calling methods such as
+ * {@link android.net.ConnectivityManager#getDefaultProxy}.
  */
 public class ProxyInfo implements Parcelable {