Fix chromecast_browser_test.

Fix chromecast_browser_test.

Use correct browser context when creating web_contents.

R=gunsch@chromium.org
BUG=

Committed: https://crrev.com/57372056895fabfb36e67b6c806420dff091213a
Cr-Commit-Position: refs/heads/master@{#309596}

[gunsch, 2014-12-23 21:48:19]

lgtm

[derekjchow1, 2014-12-23 22:00:30]

The CQ bit was checked by derekjchow@chromium.org

[commit-bot: I haz the power, 2014-12-23 22:01:21]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/818283002/1

[commit-bot: I haz the power, 2014-12-23 22:09:44]

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

[commit-bot: I haz the power, 2014-12-23 22:09:44]

Try jobs failed on following builders:
  android_chromium_gn_compile_rel on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)
  linux_chromium_gn_dbg on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[derekjchow1, 2014-12-23 22:16:51]

The CQ bit was checked by derekjchow@chromium.org

[commit-bot: I haz the power, 2014-12-23 22:17:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/818283002/1

[commit-bot: I haz the power, 2014-12-23 22:24:52]

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

[commit-bot: I haz the power, 2014-12-23 22:24:53]

Try jobs failed on following builders:
  android_chromium_gn_compile_dbg on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)

[derekjchow1, 2014-12-23 22:37:29]

The CQ bit was checked by derekjchow@chromium.org

[commit-bot: I haz the power, 2014-12-23 22:37:44]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/818283002/1

[commit-bot: I haz the power, 2014-12-23 22:46:13]

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

[commit-bot: I haz the power, 2014-12-23 22:46:14]

Try jobs failed on following builders:
  android_chromium_gn_compile_rel on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)

[derekjchow1, 2014-12-23 23:30:43]

The CQ bit was checked by derekjchow@chromium.org

[commit-bot: I haz the power, 2014-12-23 23:32:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/818283002/1

[commit-bot: I haz the power, 2014-12-23 23:40:56]

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

[commit-bot: I haz the power, 2014-12-23 23:40:57]

Try jobs failed on following builders:
  android_chromium_gn_compile_rel on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_chromiu...)

[derekjchow1, 2014-12-24 00:30:40]

The CQ bit was checked by derekjchow@chromium.org

[commit-bot: I haz the power, 2014-12-24 00:31:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/818283002/1

[commit-bot: I haz the power, 2014-12-24 00:54:52]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-24 00:55:38]

Patchset 1 (id:??) landed as
https://crrev.com/57372056895fabfb36e67b6c806420dff091213a
Cr-Commit-Position: refs/heads/master@{#309596}