Make isCaptivePortal perform both HTTP and HTTPS probes.

Also a couple of minor cleanups and logging tweaks.

Bug: 26075613
Change-Id: I67b09e96d72764179339b616072bb2ce06aabf33
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index 2394531..b1bf355 100755
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -7706,6 +7706,15 @@
         public static final String CAPTIVE_PORTAL_SERVER = "captive_portal_server";
 
         /**
+         * Whether to use HTTPS for network validation. This is enabled by default and the setting
+         * needs to be set to 0 to disable it. This setting is a misnomer because captive portals
+         * don't actually use HTTPS, but it's consistent with the other settings.
+         *
+         * @hide
+         */
+        public static final String CAPTIVE_PORTAL_USE_HTTPS = "captive_portal_use_https";
+
+        /**
          * Whether network service discovery is enabled.
          *
          * @hide