/// <summary>
/// Wraps existing view engines with ViewTrackerRazorEngine.
/// </summary>
/// <param name="application">Mvc Application</param>
/// <param name="viewEngines">View Engines</param>
public void StartTracking(HttpApplication application, ViewEngineCollection viewEngines)
{
_viewUsage = new ConcurrentDictionary <string, ulong>(_directoryHelper
.GetFiles(HostingEnvironment.ApplicationPhysicalPath, "*.cshtml", SearchOption.AllDirectories)
.ToDictionary(f => f, _ => (ulong)0));
var engines = viewEngines.Select(v => new ViewTrackerRazorEngine(v, this)).ToList();
viewEngines.Clear();
engines.ForEach(viewEngines.Add);
}