split file path constants out for split link

split file path constants out for split link

This is a follow on of work started in https://codereview.chromium.org/15310002/

TBR=brettw@chromium.org
R=cpu@chromium.org
BUG=237249
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=201279

[cpu_(ooo_6.6-7.5), 2013-05-20 22:10:43]

lgtm

achievement unlocked: all trybots are red.

[scottmg, 2013-05-20 22:32:39]

On 2013/05/20 22:10:43, cpu wrote:
> lgtm
> 
> achievement unlocked: all trybots are red.

  .__.
 (|  |)  [ all trybots are red ]
  (  )
  _)(_   [ got an lgtm anyway! ]

[commit-bot: I haz the power, 2013-05-21 00:25:51]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/scottmg@chromium.org/15495003/7

[commit-bot: I haz the power, 2013-05-21 09:44:07]

Change committed as 201279