[filebrowser] Introduce View action for supported file types (e.g. pdf).

chrome/test/data/extensions/api_test/filesystem_handler/manifest.json

 {
   "key": "MIGdMA0GCSqGSIb3DQEBAQUAA4GLADCBhwKBgQChptAQ0n4R56N03nWQ1ogR7DVRBjGo80Vw6G9KLjzZv44D8rq5Q5IkeQrtKgWyZfXevlsCe3LaLo18rcz8iZx6lK2xhLdUR+ORjsjuBfdEL5a5cWeRTSxf75AcqndQsmpwMBdrMTCZ8jQNusUI+XlrihLNNJuI5TM4vNINI5bYFQIBIw==",
   "name": "ChromeOS file system intent hanlder extension",
   "version": "0.1",
   "manifest_version": 2,
   "description": "Tests of chrome.fileSystem.* methods",
   "background": {
     "scripts": ["tab.js"]
   },
   "file_browser_handlers": [
     {
-      "id" : "TextAction",
-      "default_title" : "txt file action.",
+      "id" : "AbcAction",
+      "default_title" : "abc file action.",
       "default_icon" : "icon.png",
-      "file_filters" : [ "filesystem:*.tXt", "filesystem:*.text" ]
+      "file_filters" : [ "filesystem:*.aBc", "filesystem:*.abcfile" ]
     },
     {
-      "id" : "JpegAction",
-      "default_title" : "jpg file action",
+      "id" : "123Action",
+      "default_title" : "123 file action",
       "default_icon" : "icon.png",
-      "file_filters" : [ "filesystem:*.jpg", "filesystem:*.jpeg" ]
+      "file_filters" : [ "filesystem:*.123", "filesystem:*.1234" ]
     },
     {
       "id" : "BaseAction",
       "default_title" : "Base action",
       "default_icon" : "icon.png",
       "file_filters" : [ "filesystem:*", "filesystem:*.*" ]
     }
   ],
   "permissions": [
     "fileBrowserHandler",
     "tabs",
     "unlimitedStorage"
   ]
 }