wm: Update a lot of code to use structs from geometry.h.

I'm updating most of the code here, with a few exceptions:
- Compositor (I'll do this in a separate change)
- deprecated Window::MoveClient() and MoveComposited()
  methods
- LayoutManager (I have a simplified rewrite of this
  in-progress for http://crosbug.com/13963)

Most of this change is completely mechanical, but I'm also
simplifying how we handle moving override-redirect windows'
compositing actors to the correct place onscreen and showing,
hiding, and restacking them: instead of doing this manually
in the WindowManager class, it's done in
Window::HandleConfigureNotify() and friends.

BUG=chromium-os:1822
TEST=ran existing tests

Review URL: http://codereview.chromium.org/6902072

Change-Id: I597e258ebf9382a84f98cc62b0bc2241330bd40b