sync ui: fix text for wifi network sync control

sync ui: fix text for wifi network sync control

The checkbox controlling syncing of WiFi credentials should
be labeled "Wi-Fi networks", since that's easier for users
to understand. This CL makes it so.

BUG=chromium:436916
TEST=manual (open chrome://settings/syncSetup, verify text)

Committed: https://crrev.com/e12366500f67a1f5a2ff4b6ac8b93d1f4b036f89
Cr-Commit-Position: refs/heads/master@{#310133}

[mukesh agrawal, 2015-01-05 23:59:22]

quiche@chromium.org changed reviewers:
+ pavely@chromium.org

[mukesh agrawal, 2015-01-05 23:59:22]

quiche@chromium.org changed required reviewers:
+ pavely@chromium.org

[pavely, 2015-01-06 18:47:38]

lgtm

[mukesh agrawal, 2015-01-06 19:16:26]

The CQ bit was checked by quiche@chromium.org

[commit-bot: I haz the power, 2015-01-06 19:17:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/838523002/1

[commit-bot: I haz the power, 2015-01-06 20:25:52]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-06 20:26:44]

Patchset 1 (id:??) landed as
https://crrev.com/e12366500f67a1f5a2ff4b6ac8b93d1f4b036f89
Cr-Commit-Position: refs/heads/master@{#310133}