On Windows, we need to reconstruct the window to allow setting a new
pixel format with a different sample count.
Added some code that maintains window size/position across these changes.
Previously, just cycling through backends would cause the window to move,
as the "default" position would cycle across the screen. Now it's pinned.
BUG=skia:
Change-Id: Iecbe7a490577382043ffe5a88c910b4c0be2ed5c
Reviewed-on: https://skia-review.googlesource.com/9085
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
28b1252bab