Proposed API for window handle

[TylerLeonhardt]

For Broker support in Microsoft Authentication (#229431) we need the window handle for this API:
https://github.com/AzureAD/microsoft-authentication-library-for-js/blob/dev/lib/msal-node/docs/brokering.md#window-parenting

So, I need to be able to access the window handle from Main alllll the way in an extension.

Here's the proposal:

	export namespace env {
		/**
		 * Retrieves the native window handle of the current window.
		 *
		 * @returns A promise that resolves to a Buffer containing the native window handle.
		 */
		export function getNativeWindowHandle(): Thenable<Buffer | undefined>;
	}

[jrieken]

• use Uint8Array over Buffer
• use property over async-function
• make it init data

[TylerLeonhardt]

UInt8Array was cumbersome to pass across processes... so I landed on a base64 string. From there, an extension (Microsoft auth) can simply turn that into a Buffer Buffer.from(env.handle, 'base64') and pass it through.

New proposal:

	export namespace env {
 		/**
 		 * Retrieves a base64 representation of a native window
 		 * handle of the current window.
 		 */
 		export const handle: string | undefined;
 	}

[jrieken]

Let's keep this open to track lifecyle of this proposal

[TylerLeonhardt]

handle on env feels weird. Couple ideas:

• window.handle
• env.windowHandle

[jrieken]

I believe window.handle is the most correct but maybe a more telling name, like nativeHandle or so?

[jrieken]

what about AUX windows?