Adds experimental flag --enable-experimental-ime-features.

chrome/common/extensions/api/input_method_private.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "inputMethodPrivate",
     "platforms": ["chromeos"],
     "description": "none",
     "functions": [
       {
+        "name": "getConfig",
+        "type": "function",
+        "description": "Gets configurations for input methods.",
+        "parameters": [
+          {
+            "name": "callback",
+            "type": "function",
+            "optional": false,
+            "description": "Callback which is called with the config object.",
+            "parameters": [
+              {
+                "name": "config",
+                "type": "object",
+                "description": "The input method config object.",
+                "properties": {
+                  "isExperimentalEnabled": {"type": "boolean"}
+                }
+              }
+            ]
+          }
+        ]
+      }, {
         "name": "getInputMethods",
         "type": "function",
         "description": "Gets all whitelisted input methods.",
         "parameters": [
           {
             "name": "callback",
             "type": "function",
             "optional": false,
             "description": "Callback which is called with the input method objects.",
             "parameters": [
@@ skipping 62 matching lines @@
           {
             "name": "newInputMethodId",
             "type": "string",
             "description": "New input method which is being used."
           }
         ]
       }
     ]
   }
 ]