Move scoped_temp_dir from base to base/files

Move scoped_temp_dir from base to base/files

Also add to base namespace.

BUG=

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=168281

[brettw, 2012-11-14 21:22:33]

This is just the obvious move stuff in base, and a mechanical
search-and-replace-and-sort-header-files in the rest of the project. I did
manually check the changes.

[brettw, 2012-11-14 21:23:25]

Hmm, some include list sorting didn't work. I'll look at that.

[alexeypa (please no reviews), 2012-11-14 22:14:40]

remoting/* - lgtm

[brettw, 2012-11-16 20:15:11]

TBR=jar
as we discussed in person