RemoteMacViews: Update platform_util prefer views APIs to Cocoa APIs

Because of RemoteMacViews, we are in a world where a gfx::NativeView
may be an NSView, or it may be a handle that is used to access an
NSView that is in another process.

Utility functions, such as the platform_util:: functions, that take
a gfx::NativeView, need to be updated to handle this appropriately.

Add a band-aid fix for this particular instance (which fixes
modal dialogs in RemoteMacViews).

A more appropriate long-term solution will be required.

Change-Id: I180b9127c3344049151922580f21454aeaf48492
Reviewed-on: https://chromium-review.googlesource.com/c/1262970
Commit-Queue: ccameron <[email protected]>
Reviewed-by: Avi Drissman <[email protected]>
Reviewed-by: Elly Fong-Jones <[email protected]>
Cr-Commit-Position: refs/heads/master@{#597664}
2 files changed