Provide a different message when viewport is too small for amp-story on desktop

Currently we show the same message on desktop and mobile when the viewport is too small:

When the story is being viewed in “desktop” mode (indicated by the desktop attribute on the <amp-story> tag itself, or by the isDesktop_() function in the AmpStory class), we should change the icon and the message to convey “make your window larger” rather than “rotate your device to portrait orientation.”

[newmuis]

Whoops, sorry! Missed that notification. I think there are two criteria that must both be met to trigger this:

1. The width of the viewport must be less than 1024px.
2. The height of the viewport must be less than the width.

I do agree; I think the warning is shown appropriately for those screen sizes, but you’re right that we may not be able to use isDesktop_() to determine when to change the message. Maybe for now we can use isAndroid() and isIos() and only change the message when we’re not on Android or iOS? I suppose what we’re really trying to detect is devices where “rotate your device” doesn’t make sense. I don’t think there’s any way to really determine that through the Orientation API, so a proxy of Android and iOS may have to suffice.

[sanjsanj]

When you have time have a look pls @newmuis cheers!