Add guest mode functionality (2/4)

Add a flag to enable() to start Bluetooth in restricted
mode. In restricted mode, all devices that are paired during
restricted mode are deleted upon leaving restricted mode.
Right now restricted mode is only entered while a guest
user is active.

Bug: 27410683
Change-Id: I19ff91d1d7fb8c60230fee7a05d32574b5b2aeda
diff --git a/btif/include/btif_api.h b/btif/include/btif_api.h
index dcaecfc..ed67b9e 100644
--- a/btif/include/btif_api.h
+++ b/btif/include/btif_api.h
@@ -89,6 +89,23 @@
 
 /*******************************************************************************
 **
+** Function         is_restricted_mode
+**
+** Description      Checks if BT was enabled in restriced mode. In restricted
+**                  mode, bonds that are created are marked as temporary.
+**                  These bonds persist until we leave restricted mode, at
+**                  which point they will be deleted from the config. Also
+**                  while in restricted mode, the user can access devices
+**                  that are already paired before entering restricted mode,
+**                  but they cannot remove any of these devices.
+**
+** Returns          bool
+**
+*******************************************************************************/
+bool is_restricted_mode(void);
+
+/*******************************************************************************
+**
 ** Function         btif_get_adapter_properties
 **
 ** Description      Fetches all local adapter properties