MacViews: Allow the BridgedNativeWidgetTest to focus its textfield

MacViews: Allow the BridgedNativeWidgetTest to focus its textfield

Some tests regressed in r316774 because the way edit commands were
dispatched in BridgedContentView changed from going directly to the
TextInputClient to instead go through the InputMethod.

r316774 included a check added to views::Textfield to ensure any
scheduled edit command had been processed before scheduling a new one.
Some tests failed that check: Because the textfield did not have focus,
the dispatch of the event that would commit the edit command was not
being received.

This CL ensures the textfield requests focus in the test.

Fixes (mac-only) views_unittests:
BridgedNativeWidgetTest.TextInput_MoveLeftRight
BridgedNativeWidgetTest.TextInput_DeleteBackward
BridgedNativeWidgetTest.TextInput_DeleteForward

BUG=454353
Committed: https://crrev.com/6d2b33248c109d735b041eed2e8229fa0c95d4cf
Cr-Commit-Position: refs/heads/master@{#317715}

[tapted, 2015-02-23 07:38:36]

tapted@chromium.org changed reviewers:
+ andresantoso@chromium.org

[tapted, 2015-02-23 07:39:46]

Hi Andre, please take a look

[Andre, 2015-02-23 18:03:33]

LGTM

[tapted, 2015-02-24 00:17:26]

The CQ bit was checked by tapted@chromium.org

[commit-bot: I haz the power, 2015-02-24 00:19:53]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/941943003/1

[commit-bot: I haz the power, 2015-02-24 01:10:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-24 01:10:55]

Patchset 1 (id:??) landed as
https://crrev.com/6d2b33248c109d735b041eed2e8229fa0c95d4cf
Cr-Commit-Position: refs/heads/master@{#317715}