Straighten up includes of host_desktop.h/host_desktop_type.h

Straighten up includes of host_desktop.h/host_desktop_type.h

This CL does the following:
- Includes //ui/gfx/host_desktop_type.h everywhere that ui::HostDesktopType is
  used
- Eliminates //chrome/browser/ui/host_desktop.h includes where they are not
  needed
- Does necessary fixup for ICWY violations that were revealed by the above
  changes

BUG=528880

[blundell, 2015-09-11 14:01:08]

blundell@chromium.org changed reviewers:
+ sky@chromium.org

[blundell, 2015-09-11 14:01:09]

I think that this one would be safe to rubberstamp or spot-check if you want :).

[sky, 2015-09-11 16:05:12]

I don't see ui/gfx/host_desktop_type.h. Am I missing something?

[sky, 2015-09-11 16:05:56]

Never mind, Sadrul responded to the other patch (where you create it), so I saw
this one first. Will look at the one that adds ui/gfx/host_desktop.h now.

[blundell, 2015-09-14 08:01:02]

Closing this patch, as the parent CL is not the approach we're going to take.