Move WebInputEvent from public/web to public/platform

Move WebInputEvent from public/web to public/platform

Moving WebInputEvent into public/platform lets us refer to it directly in core, which will let us remove the PlatformFooEvent classes.

The final pipeline will be:
1) mojo::InputEvent (IPC type, device pixels)
2) blink::WebInputEvent (platform abstraction, logical pixels)
3) blink::Event (DOM type, logical pixels)

If mojo::InputEvent used logical pixels, it would probably be easier to just
use mojo::InputEvent as the platform abstraction, but instead we use the
mojo-to-blink conversion to translate between device and logical pixels, like
we do everywhere else in Sky.

R=eseidel@google.com, eseidel@chromium.org

Committed: https://chromium.googlesource.com/external/mojo/+/db9953e5ff43d6f47f2ca9a2ed15429820faffba

[eseidel1, 2015-01-20 01:59:59]

eseidel@google.com changed reviewers:
+ eseidel@google.com

[eseidel1, 2015-01-20 01:59:59]

lgtm

Hopefully you used the move_source_file script and didn't do this by hand. :)

[abarth-chromium, 2015-01-20 02:39:31]

On 2015/01/20 at 01:59:59, eseidel wrote:
> lgtm
> 
> Hopefully you used the move_source_file script and didn't do this by hand. :)

I didn't but I will next time.  :)

[abarth-chromium, 2015-01-20 02:39:44]

Committed patchset #2 (id:20001) manually as
db9953e5ff43d6f47f2ca9a2ed15429820faffba (presubmit successful).