Move latin1_string_conversions to base

Move latin1_string_conversions to base

Unfortunately, we can't keep this function in webkit/glue because not everyone
who links in Blink depends on webkit/glue. For example, cc uses WebString but
doesn't depend on webkit/glue.

IMHO, the best solution to all these constraints is to put this function in
base. It's concerned with concepts that make sense in base (strings and
character sets). The only thing odd about the function is that it accepts
Latin-1 or UTF-16, which is because of the underlying string representation in
Blink.

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=203003

[abarth-chromium, 2013-05-29 01:35:03]

@darin: Would you be willing to review this CL?

[abarth-chromium, 2013-05-29 18:32:22]

@brettw: Would you be willing to LGTM this CL?  You said "ok" the idea in
another CL, but I wanted to get the official stamp before landing this one.

Thanks!

[darin (slow to review), 2013-05-29 19:11:15]

LGTM

[abarth-chromium, 2013-05-29 20:24:55]

Thanks!

[commit-bot: I haz the power, 2013-05-29 20:25:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/abarth@chromium.org/15732022/1

[commit-bot: I haz the power, 2013-05-29 23:21:33]

Change committed as 203003