[Mac] Fix download item text sometimes being misaligned.

[Mac] Fix download item text sometimes being misaligned.

There's two possible stable values for |titleY_|,
kPrimaryTextPosTop - when status message is visible,
kPrimaryTextOnlyPosTop - when status message is not visible.

There was an inconistency how this was being initialized -
as isStatusTextVisible_ was being set to NO but the value
was set to kPrimaryTextPosTop.

The text would then be misaligned if the code would take
the -hideSecondaryTitle in -setStateFromDownload:.

This CL fixes the issue and updates the test to check this.

BUG=484848
Committed: https://crrev.com/293783badd2363e2135d593cb5e36e04a163c92f
Cr-Commit-Position: refs/heads/master@{#329305}

[Alexei Svitkine (slow), 2015-05-11 21:44:13]

asvitkine@chromium.org changed reviewers:
+ asanka@chromium.org

[asanka, 2015-05-11 23:47:42]

lgtm

[Alexei Svitkine (slow), 2015-05-12 00:57:31]

The CQ bit was checked by asvitkine@chromium.org

[commit-bot: I haz the power, 2015-05-12 00:59:16]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1130903004/1

[commit-bot: I haz the power, 2015-05-12 01:09:29]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-12 01:11:01]

Patchset 1 (id:??) landed as
https://crrev.com/293783badd2363e2135d593cb5e36e04a163c92f
Cr-Commit-Position: refs/heads/master@{#329305}