[Extensions] Remove the "use_movable_types" entry from idl/json files

extensions/common/api/system_network.idl

Index: extensions/common/api/system_network.idl
diff --git a/extensions/common/api/system_network.idl b/extensions/common/api/system_network.idl
index 6449267b629c81439009c9fa8f4090975ec6ea74..bbc28ae9dd51d2e16ed606bdb5392615fcdcd78f 100644
--- a/extensions/common/api/system_network.idl
+++ b/extensions/common/api/system_network.idl
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 // Use the <code>chrome.system.network</code> API.
-[use_movable_types=true] namespace system.network {
+namespace system.network {
   dictionary NetworkInterface {
     // The underlying name of the adapter. On *nix, this will typically be
     // "eth0", "wlan0", etc.