Do not break lines when width is not specified.

Do not break lines when width is not specified.

In case SetAllowCharacterBreak(true) is specified but width is not
specified yet, nobody can stop gfx::ElideRectangleText() to wrap
the text at very narrow width. But when the width is not specified,
the ideal lines is expected (so that the label can be layouted
based on the size).

BUG=469559
R=sky@chromium.org
TEST=the new test case covers

Committed: https://crrev.com/4672257ac71a14be683b4f5a4b54a402cf0e493b
Cr-Commit-Position: refs/heads/master@{#321854}

[sky, 2015-03-23 19:19:35]

LGTM

[Jun Mukai, 2015-03-23 19:21:37]

The CQ bit was checked by mukai@chromium.org

[commit-bot: I haz the power, 2015-03-23 19:21:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1029593004/1

[commit-bot: I haz the power, 2015-03-23 21:22:27]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-23 21:22:51]

Patchset 1 (id:??) landed as
https://crrev.com/4672257ac71a14be683b4f5a4b54a402cf0e493b
Cr-Commit-Position: refs/heads/master@{#321854}