Fix a mouse lock problem on Windows where in clicks outside the web page would also cause mouse loc…

Fix a mouse lock problem on Windows where in clicks outside the web page would also cause mouse lock to happen.

This fixes an issue with the mouse locking code on Windows where in if a page entered a mouse lock state and exited
it via the Esc key, subsequently clicking outside the page would cause the lock prompt to display again. This was because
RenderWidgetHostViewAura grabs capture on all platforms including Windows. On Windows the capture happens elsewhere in the
mouse handler. However when the mouse release comes in it is possible that we are already in the mouse locked state and
hence the capture is never released.

Fix is to release capture on all platforms.

BUG=526378
R=scheib
TBR=jam

Committed: https://crrev.com/c922b25f080de27ebe891adff689e9b56ffeaf12
Cr-Commit-Position: refs/heads/master@{#347122}

[scheib, 2015-09-02 15:28:12]

LGTM

[ananta, 2015-09-02 23:15:16]

ananta@chromium.org changed reviewers:
+ sky@chromium.org

[ananta, 2015-09-02 23:15:33]

+sky for content renderer host owner review

[sky, 2015-09-02 23:56:08]

LGTM

[ananta, 2015-09-03 00:11:57]

The CQ bit was checked by ananta@chromium.org

[ananta, 2015-09-03 00:30:32]

The CQ bit was unchecked by ananta@chromium.org

[ananta, 2015-09-03 00:30:37]

The CQ bit was checked by ananta@chromium.org

[commit-bot: I haz the power, 2015-09-03 00:31:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1324083002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1324083002/1

[commit-bot: I haz the power, 2015-09-03 00:51:21]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-09-03 00:51:22]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[ananta, 2015-09-03 06:00:41]

ananta@chromium.org changed reviewers:
+ jam@chromium.org

[ananta, 2015-09-03 06:00:57]

TBR'ing jam for content owners.

[ananta, 2015-09-03 06:01:11]

The CQ bit was checked by ananta@chromium.org

[commit-bot: I haz the power, 2015-09-03 06:01:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1324083002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1324083002/1

[commit-bot: I haz the power, 2015-09-03 06:43:19]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-03 06:44:01]

Patchset 1 (id:??) landed as
https://crrev.com/c922b25f080de27ebe891adff689e9b56ffeaf12
Cr-Commit-Position: refs/heads/master@{#347122}