RemoteMacViews: Make certificate and file dialogs better

The certificate and file selection dialogs have not been adapted to be
able to run across processes using mojo.

At present, these dialogs appear behind their expected window, and
appear in the Chrome process. Make this situation better by making
them appear in front of their window (and, in front of everything).

Because some of these positioning decisions are made before the
true window geometry has been communicated back to the browser process,
more aggressively push geometry changes to the in-browser-process
NSWindow.

Bug: 913303
Change-Id: Ife2fbddcd758ee0b028743a916d12cf8ce0f41f3
Reviewed-on: https://chromium-review.googlesource.com/c/1378017
Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Commit-Queue: ccameron <ccameron@chromium.org>
Cr-Commit-Position: refs/heads/master@{#616772}
7 files changed