adb: wait for adbd to die and respawn in root/unroot.

Bug: http://b/19749057
Change-Id: I57dbc113803b6fd3016c1801410be0f4023245d9
diff --git a/adb/adb_client.cpp b/adb/adb_client.cpp
index db9b710..d29c08e 100644
--- a/adb/adb_client.cpp
+++ b/adb/adb_client.cpp
@@ -50,6 +50,15 @@
     __adb_serial = serial;
 }
 
+void adb_get_transport(TransportType* type, const char** serial) {
+    if (type) {
+        *type = __adb_transport;
+    }
+    if (serial) {
+        *serial = __adb_serial;
+    }
+}
+
 void adb_set_tcp_specifics(int server_port)
 {
     __adb_server_port = server_port;