Make it possible to change the viewport size

Make it possible to change the viewport size

This makes it possible to change the viewport size
which mojo is using.  The sky debugger uses this new
API to set the viewport to something closer to mobile
instead of 800x600 ancient desktop size. :)

Still the (800, 600) constant is prevelant throughout
mojo (just search for it) and mojo does not seem to
fully update when the viewport size changes, so we actually
only see 320x600 pixels instead of 320x640 in
sky debugger after this change.

Mostly this change is about validating that this is the
correct way to plumb this information.

R=sky@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/6a7fabed4d6c8ddfbc932b2bd6d36d20e6337b2a

[sky, 2014-10-30 03:23:57]

LGTM with the following addressed. And yes, this is the route I was thinking.

https://codereview.chromium.org/692693002/diff/1/mojo/services/view_manager/c...
File mojo/services/view_manager/connection_manager.h (right):

https://codereview.chromium.org/692693002/diff/1/mojo/services/view_manager/c...
mojo/services/view_manager/connection_manager.h:182: 
nit: no empty line here (similar to 174/175 above)

https://codereview.chromium.org/692693002/diff/1/mojo/services/view_manager/c...
mojo/services/view_manager/connection_manager.h:183: virtual void
SetViewportSize(SizePtr size) override;
no virtual (174 has it right, 180 wrong).

https://codereview.chromium.org/692693002/diff/1/mojo/services/view_manager/c...
mojo/services/view_manager/connection_manager.h:185: 
nit: only one empty line, not two.

https://codereview.chromium.org/692693002/diff/1/mojo/services/view_manager/d...
File mojo/services/view_manager/display_manager.h (right):

https://codereview.chromium.org/692693002/diff/1/mojo/services/view_manager/d...
mojo/services/view_manager/display_manager.h:48: void SetViewportSize(const
gfx::Size&);
Chrome/Google style is to always have names in (that match) in definition and
declaration.

https://codereview.chromium.org/692693002/diff/1/mojo/services/window_manager...
File mojo/services/window_manager/window_manager_app.h (right):

https://codereview.chromium.org/692693002/diff/1/mojo/services/window_manager...
mojo/services/window_manager/window_manager_app.h:84: void
SetViewportSize(gfx::Size);
const gfx::Size& and same comment about names.

[eseidel, 2014-10-30 21:20:50]

Committed patchset #2 (id:20001) manually as
6a7fabed4d6c8ddfbc932b2bd6d36d20e6337b2a (presubmit successful).