There's no simple, cross-platform way to register protocol handlers in Electron. Every OS requires a different solution. This seems like something that Electron should smooth over.

There's already a W3C API for this: [`Navigator.registerProtocolHandler`](https://developer.mozilla.org/en-US/docs/Web/API/Navigator/registerProtocolHandler). Can Electron implement it?

atom/browser/browser.h
#ifndef ATOM_BROWSER_BROWSER_H_
#define ATOM_BROWSER_BROWSER_H_
#include <string>
#include <vector>
#include "base/macros.h"
#include "base/compiler_specific.h"
#include "base/observer_list.h"
#include "base/strings/string16.h"
#include "atom/browser/browser_observer.h"
#include "atom/browser/window_list_observer.h"
#if defined(OS_WIN)
#include "base/files/file_path.h"
#endif
namespace base {
class FilePath;
}
namespace ui {
class MenuModel;
}
namespace gfx {
class Image;
}
namespace atom {
class LoginHandler;
class Browser : public WindowListObserver {