This member overrides WebControl.SaveViewState(), and more complete documentation might be available in that topic.
Saves any server control view state changes that have occurred since the time the page was posted back to the server.
Assembly: System.Web (in System.Web.dll)
View state is the accumulation of the values of the properties for the ChangePassword control. These values are automatically placed in the ViewState property for the ChangePassword control, which is an instance of the StateBag class. The value for the ViewState property is then persisted to a string object after the save state stage of the ChangePassword control life cycle. For more information, see ASP.NET Page Life Cycle Overview.
When view state is saved, this string object is returned to the client as a variable that is stored in an HTML <input type="hidden" /> element. When you author custom server controls, you can improve efficiency by overriding the method and modifying the ViewState property for the ChangePassword control.