Add developer option for freeform window support (1/2)

Also disable default force-resizable on non-user builds.

Bug: 25276672
Bug: 24815256
Bug: 26294625
Bug: 26294534
Change-Id: I5b31e494c993d2d9dad175b94b4f30637e8f3718
diff --git a/core/java/android/provider/Settings.java b/core/java/android/provider/Settings.java
index b883f9c..4eaee0b 100644
--- a/core/java/android/provider/Settings.java
+++ b/core/java/android/provider/Settings.java
@@ -6374,6 +6374,13 @@
         public static final String DEVELOPMENT_FORCE_RESIZABLE_ACTIVITIES
                 = "force_resizable_activities";
 
+        /**
+         * Whether to enable experimental freeform support for windows.
+         * @hide
+         */
+        public static final String DEVELOPMENT_ENABLE_FREEFORM_WINDOWS_SUPPORT
+                = "enable_freeform_support";
+
        /**
         * Whether user has enabled development settings.
         */