win vs2015: avoid variable shadowing warning in url_canon.h

win vs2015: avoid variable shadowing warning in url_canon.h

d:\src\cr2\src\url\url_canon.h(737): error C2220: warning treated as error - no 'object' file generated
d:\src\cr2\src\url\url_canon.h(737): warning C4459: declaration of 'empty_string' hides global declaration
d:\src\cr2\src\url\gurl.cc(22): note: see declaration of '`anonymous-namespace'::empty_string'

R=brettw@chromium.org
BUG=440500
Committed: https://crrev.com/df75e1de1238c157580ec10d6f9478d7222b4d69
Cr-Commit-Position: refs/heads/master@{#317431}

[brettw, 2015-02-20 21:02:13]

lgtm

[scottmg, 2015-02-20 21:40:55]

The CQ bit was checked by scottmg@chromium.org

[commit-bot: I haz the power, 2015-02-20 21:41:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/937473003/1

[commit-bot: I haz the power, 2015-02-20 22:42:44]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-20 22:43:20]

Patchset 1 (id:??) landed as
https://crrev.com/df75e1de1238c157580ec10d6f9478d7222b4d69
Cr-Commit-Position: refs/heads/master@{#317431}