Built-in simple icons (magnifine glass, plus sign, trash can, etc) for ToolBarItem icon

Is there a simple way to add well-known icons (magnifine glass, plus sign, trash can, etc) to a ToolBarItem?

Assuming a happy path Android API19+ only deployment can/should I reference the built-in Android icons? Based on this code it looks like I need to ship my own:

• https://github.com/xamarin/xamarin-forms-samples/tree/master/MobileCRM/MobileCRM.Android/Resources

These posts were helpful:

• http://stackoverflow.com/questions/24664700/how-to-use-androids-built-in-icons
• http://forums.xamarin.com/discussion/19225/icon-image-on-toolbar-item-in-xamarin-forms
• https://github.com/svenkapudija/Android-Action-Bar-Icons

I couldn't find any examples on how to dynamically set an icon for a ToolBarItem based on the runtime platform in XAML. These examples display an image in the main content of the page, not in a ToolBarItem:

• https://github.com/xamarin/xamarin-forms-samples/tree/master/WorkingWithImages/WorkingWithImages