Rename Native messaging hosts directory to native_hosts.

Rename Native messaging hosts directory to native_hosts.

Previously the directory name contained spaces which is problematic
when applying patches on trybots. In the future this directory 
will go away with the new native host installation mechanism, so the name
doesn't really matter.

BUG=142915
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=175958

[Matt Perry, 2013-01-10 00:09:44]

LGTM as long as this is temporary. (Chrome's convention is to use Folder Name as
the naming scheme for folders in the user's profile directory, so I'd like to
preserve that.)

Could you add a BUG number to the CL description pointing to the native
messaging bug?

[Sergey Ulanov, 2013-01-10 00:30:39]

On 2013/01/10 00:09:44, Matt Perry wrote:
> LGTM as long as this is temporary. (Chrome's convention is to use Folder Name
as
> the naming scheme for folders in the user's profile directory, so I'd like to
> preserve that.)
> 
> Could you add a BUG number to the CL description pointing to the native
> messaging bug?

Done.

[commit-bot: I haz the power, 2013-01-10 00:36:36]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sergeyu@chromium.org/11833021/2001

[commit-bot: I haz the power, 2013-01-10 00:36:41]

Can't process patch for file
chrome/test/data/native_messaging/native_hosts/empty_app.py.
Unexpected git diff output name Hosts/empty_app.py
b/chrome/test/data/native_messaging/native_hosts/empty_app.py.

[Sergey Ulanov, 2013-01-10 00:47:26]

On 2013/01/10 00:36:41, I haz the power (commit-bot) wrote:
> Can't process patch for file
> chrome/test/data/native_messaging/native_hosts/empty_app.py.
> Unexpected git diff output name Hosts/empty_app.py
> b/chrome/test/data/native_messaging/native_hosts/empty_app.py.

That's exactly why I need this change.