I know the question is for base.js , there is also a compiled library in one JS file.
<script src="http://resources.programmingclosure.com/closure-lite.js"></script>
Source : http://www.programmingclosure.com/closure-lite/
Closure Lite API
Closure Lite includes the following APIs from Closure:
- goog.array
- goog.Disposable
- goog.dispose
- goog.dom
- goog.dom.DomHelper
- goog.events.NodeType
- goog.dom.TagName
- goog.dom.classes
- goog.dom.xml
- goog.events
- goog.events.BrowserEvent
- goog.events.Event
- goog.events.EventHandler
- goog.events.EventType
- goog.events.EventTarget
- goog.events.KeyEvent
- goog.events.KeyCodes
- goog.events.KeyHandler
- goog.events.Listener
- goog.functions
- goog.json
- goog.math.Box
- goog.math.Coordinate
- goog.math.Rect
- goog.math.Size
- goog.net.ErrorCode
- goog.net.EventType
- goog.net.XhrIo
- goog.net.XhrMonitor
- goog.net.XmlHttp
- goog.object
- goog.string
- goog.structs
- goog.structs.Map
- goog.structs.Set
- goog.style
- goog.Timer
- goog.userAgent
- goog.userAgent.product
- goog.window
EDIT : from http://www.programmingclosure.com/closure-lite/
A single JavaScript file that contains the core of the Closure Library
Closure Lite aims to solve this problem by providing the core of the Closure Library in a single, minified JavaScript file that can be included in your own web page.