Support the removal of only session cookies or persistent cookies

extensions/common/api/web_view_internal.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": "webViewInternal",
     "description": "none",
     "compiler_options": {
       "implemented_in": "extensions/browser/api/guest_view/web_view/web_view_internal_api.h"
     },
     "types": [
       {
         "id": "DataTypeSet",
         "type": "object",
         "description": "A set of data types. Missing data types are interpreted as <code>false</code>.",
         "properties": {
           "appcache": {
             "type": "boolean",
             "optional": true,
             "description": "Websites' appcaches."
           },
           "cookies": {
             "type": "boolean",
             "optional": true,
             "description": "The browser's cookies."

[lazyboy, 2017/02/15 21:45:27]

Add a note saying this will remove all cookies including session cookies and
persistent ones.

[lfg, 2017/02/15 22:44:01]

Done.

           },
+          "sessionCookies": {
+            "type": "boolean",
+            "optional": true,
+            "description": "The browser's session cookies."

[lazyboy, 2017/02/15 21:45:27]

Here and also for other places: replace browser's with WebSites', since this
applies to <webview> but not entire browser.

[lfg, 2017/02/15 22:44:01]

Done.

+          },
+          "persistentCookies": {
+            "type": "boolean",
+            "optional": true,
+            "description": "The browser's persistent cookies."
+          },
           "fileSystems": {
             "type": "boolean",
             "optional": true,
             "description": "Websites' file systems."
           },
           "indexedDB": {
             "type": "boolean",
             "optional": true,
             "description": "Websites' IndexedDB data."
           },
@@ skipping 682 matching lines @@
             "type": "function",
             "description": "Called when deletion has completed.",
             "optional": true,
             "parameters": []
           }
         ]
       }
     ]
   }
 ]