RemoteMacViews: Clean up SetBounds and SetSize

Remove the host-side function GetBoundsOffsetForParent, and pass the
one parameter that it needs from the host-side,
PositionWindowInScreenCoordinates, as a parameter during
initialization (over mojo). Move the computation of the parent offset
over to the viewer process.

Move the implementation of the function NativeWidgetMac::CenterWindow
from the host-side to the viewer-side, with the size argument passed
over mojo.

Bug: 859152
Change-Id: I48b7a3485637383a9f6dc6a3812b4c25d45a3754
Reviewed-on: https://chromium-review.googlesource.com/c/1272679
Commit-Queue: ccameron <[email protected]>
Reviewed-by: Robert Sesek <[email protected]>
Reviewed-by: Elly Fong-Jones <[email protected]>
Cr-Commit-Position: refs/heads/master@{#598534}
6 files changed