file_manager: getFileTasks() to return Drive apps iff all files are on Drive

chrome/common/extensions/api/file_browser_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":"fileBrowserPrivate",
     "compiler_options": {
       "implemented_in": "chrome/browser/chromeos/extensions/file_manager/file_browser_private_api_functions.h"
     },
@@ skipping 10 matching lines @@
             "description": "The unique identifier of the task."
           },
           "title": {
             "type": "string",
             "description": "Task title (ex. App name)."
           },
           "iconUrl": {
             "type": "string",
             "description": "Task icon url (from chrome://extension-icon/...)"
           },
-          "driveApp": {
-            "type": "boolean",
-            "description": "True if this is Drive App."
-          },
           "isDefault": {
             "type": "boolean",
             "description": "True if this task is a default task for the selected files."
           }
         }
       },
       {
         "id": "VolumeInfo",
         "type": "object",
         "description": "Mounted disk volume information.",
@@ skipping 1277 matching lines @@
       },
       {
         "name": "onDriveConnectionStatusChanged",
         "type": "function",
         "description": "Fired when the active network connection state changes. The network connection state can be retrieved via 'getDriveConnectionState'.",
         "parameters": []
       }
     ]
   }
 ]