Remove command line/field trial support and configs for Isolate Extensions.

extensions/common/api/test.json

 // Copyright 2014 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": "test",
     "description": "none",
     "functions": [
       {
@@ skipping 40 matching lines @@
                   },
                   "testDataDirectory": {
                     "type": "string",
                     "description": "file:/// URL for the API test data directory."
                   },
                   "testWebSocketPort": {
                     "type": "integer",
                     "description": "The port on which the test WebSocket server is listening.",
                     "minimum": 0,
                     "maximum": 65535
-                  },
-                  "isolateExtensions": {
-                    "type": "boolean",
-                    "description": "Whether or not extensions are running in site isolation mode."
                   }
                 }
               }
             ]
           }
         ]
       },
       {
         "name": "notifyFail",
         "type": "function",
@@ skipping 341 matching lines @@
             "properties": {
               "data": { "type": "string", "description": "Additional information." },
               "lastMessage": { "type": "boolean", "description": "True if this was the last message for this test" }
             }
           }
         ]
       }
     ]
   }
 ]