Clean up location bar offset update tracking

We pass cc::CompositorFrameMetadata around to a few places - a couple of which are interested in the location bar position, and each responsible for attempting to synchronize updates to this with the compositor.

The touch editing menu implementation needs to be aware of location bar position updates, but there's currently no good way of plumbing this in. It seems we've hit this issue in the past but just worked around it rather than fixing it, eg:

https://git.launchpad.net/oxide/tree/shared/browser/oxide_render_widget_host_view.cc?id=40441702cbbe4e4e45a70d0571dbbbb5a63fb1eb#n456

This code works around the fact that the touch handle drawables aren't aware of location bar position updates, but they should be.

Also, where coordinates are transformed for the location bar position isn't very consistent - eg, input events are transformed in qt/, whereas coordinates for the popup menu and other bits are transformed in shared/.

Time to clean this up.