Add parsers for Drive v2 Change/ChangeList/Parents

chrome/test/data/chromeos/drive/filelist.json

 {
  "kind": "drive#fileList",
  "etag": "\"WtRjAPZWbDA7_fkFjc5ojsEvDEF/zyHTfoHpnRHovyi8bWpwK0DXABC\"",
  "selfLink": "https://www.googleapis.com/drive/v2/files",
  "nextPageToken": "EAIaggELEgA6egpi96It9mH_____f_8AAP__AAD_okhU-cHLz83KzszMxsjMzs_RyNGJnridyrbHs7u9tv8AAP__AP7__n__AP8AokhU-cHLz83KzszMxsjMzs_RyNGJnridyrbHs7u9tv8A__4QZCEiXPTi_wtIgTkAAAAAngnSXUgCDEAAIgsJPgart10AAAAABC",
  "nextLink": "https://www.googleapis.com/drive/v2/files?pageToken=EAIaggELEgA6egpi96It9mH_____f_8AAP__AAD_okhU-cHLz83KzszMxsjMzs_RyNGJnridyrbHs7u9tv8AAP__AP7__n__AP8AokhU-cHLz83KzszMxsjMzs_RyNGJnridyrbHs7u9tv8A__4QZCEiXPTi_wtIgTkAAAAAngnSXUgCDEAAIgsJPgart10AAAAABC",
  "items": [
   {
    "kind": "drive#file",
    "id": "0B4v7G8yEYAWHUmRrU2lMS2hLABC",
@@ skipping 57 matching lines @@
     "starred": true,
     "hidden": false,
     "trashed": false,
     "restricted": false,
     "viewed": true
    },
    "createdDate": "2012-07-27T04:54:09.686Z",
    "modifiedDate": "2012-07-27T04:54:11.030Z",
    "modifiedByMeDate": "2012-07-27T04:54:11.030Z",
    "lastViewedByMeDate": "2012-07-27T04:54:11.030Z",
-   "parents": [
-    {
-     "kind": "drive#parentReference",
-     "id": "0AIv7G8yEYAWHUk9ABC",
-     "selfLink": "https://www.googleapis.com/drive/v2/files/1Pc8jzfU1ErbN_eucMMqdqzY3eBm0v8sxXm_1CtLxABC/parents/0AIv7G8yEYAWHUk9ABC",
-     "parentLink": "https://www.googleapis.com/drive/v2/files/0AIv7G8yEYAWHUk9ABC",
-     "isRoot": true
-    }
-   ],

[kochi, 2012/08/02 09:16:15]

Some file may not contain parents field.
In that case we assume the file is under the root directory.

[satorux1, 2012/08/02 16:41:51]

Please add some comment on this in the patch description.

[kochi, 2012/08/02 17:16:47]

Done.

    "exportLinks": {
     "application/msword": "https://docs.google.com/feeds/download/documents/export/Export?id=1Pc8jzfU1ErbN_eucMMqdqzY3eBm0v8sxXm_1CtLxABC&exportFormat=doc",
     "text/html": "https://docs.google.com/feeds/download/documents/export/Export?id=1Pc8jzfU1ErbN_eucMMqdqzY3eBm0v8sxXm_1CtLxABC&exportFormat=html",
     "application/pdf": "https://docs.google.com/feeds/download/documents/export/Export?id=1Pc8jzfU1ErbN_eucMMqdqzY3eBm0v8sxXm_1CtLxABC&exportFormat=pdf"
    },
    "userPermission": {
     "kind": "drive#permission",
     "etag": "\"WtRjAPZWbDA7_fkFjc5ojsEvDEF/LKOJhhwatz2OKj-OblM3EvO8XYZ\"",
     "id": "me",
     "role": "owner",
@@ skipping 45 matching lines @@
    "quotaBytesUsed": "0",
    "ownerNames": [
     "Test User"
    ],
    "lastModifyingUserName": "Test User",
    "editable": true,
    "writersCanShare": true
   }
  ]
 }