Should support manually growing an overflowing bottom sheet

[Hixie]

We do this:

Bottom sheets slide up from the bottom of the screen and initially cover a portion of the screen.
The initial height of a bottom sheet is relative to the height of the list items (or grid rows) it contains. A bottom sheet should not initially have a height beyond its 16:9 ratio keyline, depending on how much content it contains.

We don't do this:

Bottom sheets may be swiped up to fill the height of the screen, with content that then scrolls internally.

When displaying a long list, modal bottom sheets can scroll internally and expand past the 16:9 keyline.

The spec talks about how far it can grow in its rested state:

When displaying menu items, fully-expanded modal bottom sheets maintain a minimum 8dp distance from the bottom of the app bar.

I believe the above means non-fully-expanded modal bottom sheets. If you expand fully, you're supposed to take over the toolbar:

Fully-expanded modal bottom sheets provide an X in the app bar.

https://www.google.com/design/spec/components/bottom-sheets.html

[Hixie]

One thing we could do here is for BottomSheet (previously _BottomSheetDragController) to put a Block inside itself and use that to determine the max height (right now the height is passed in).

[Hixie]

@HansMuller sounds like there's starting to be demand for this, FWIW.

[apwilson]

Hit this issue today. Kind of annoying as I then need to wrap my content in a Block which then disables the modal bottom sheet pull up/down behaviour