Add a System.Secure setting for the Autofill server URL.

The Autofill server is now configured as a system setting. Add
that setting and a method to be called over JNI from the chrome
stack to retrieve it.

See also external/chromium change I3a22ae42402f52207eee2d0d9df64700cb7c9f45

Bug: 4515820
Change-Id: I0aa85c5bef834b1120baaabdc2dd2e4e607a63b6
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index ad32047..e2f2fe2 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -3853,6 +3853,10 @@
         /** Timeout in milliseconds to wait for NTP server. {@hide} */
         public static final String NTP_TIMEOUT = "ntp_timeout";
 
+        /** Autofill server address (Used in WebView/browser). {@hide} */
+        public static final String WEB_AUTOFILL_QUERY_URL =
+            "web_autofill_query_url";
+
         /**
          * @hide
          */