[Extensions API] Remove inline enums

extensions/common/api/bluetooth_private.json

 [
   {
     "namespace": "bluetoothPrivate",
     "description": " Use the <code>chrome.bluetoothPrivate</code> API to control the Bluetooth\n adapter state and handle device pairing.",
     "compiler_options": {
       "implemented_in": "extensions/browser/api/bluetooth/bluetooth_private_api.h"
     },
     "functions": [
       {
         "name": "setAdapterState",
@@ skipping 202 matching lines @@
           },
           "passkey": {
             "optional": true,
             "name": "passkey",
             "type": "integer",
             "description": "An integer between 0-999999 set in response to <code>requestPasskey</code>."
           }
         }
       },
       {
+        "id": "TransportType",
+        "type": "string",
+        "enum": [ "le", "bredr", "dual"]
+      },
+      {
         "type": "object",
         "id": "DiscoveryFilter",
         "properties": {
           "transport": {
+            "$ref": "TransportType",
             "optional": true,
             "name": "transport",
-            "type": "string",
-            "enum": [ "le", "bredr", "dual"],
             "description": "Transport type."
           },
           "uuids": {
             "name": "uuids",
             "optional": true,
             "choices": [
               {"type": "string", "name": "uuid of service"},
               {"type": "array",  "items": {"type": "string"}, "name": "array of uuids"}
             ]
           },
           "rssi": {
             "optional": true,
             "name": "rssi",
             "type": "integer",
             "description": "RSSI ranging value. Only devices with RSSI higher than this value will be reported."
           },
           "pathloss": {
             "optional": true,
             "name": "pathloss",
             "type": "integer",
             "description": "Pathloss ranging value. Only devices with pathloss lower than this value will be reported."
           }
         }
       }
     ]
   }
 ]