In this way, we can prevent the close of window by using beforeunload handler.
Include APIs: shell.showItemInFolder shell.openItem shell.openExternal shell.moveItemToTrash
The platform_util files just come from chrome/browser/ with slight modifications so it doesn't depend on grit/generate_resources.h, which is not availabe in libchromiumcontent because it's generated by chrome's chrome/app/generated_resources.grd.
