Seperate creation of WebContents and window tree in CastContentWindow

Seperate creation of WebContents and window tree in CastContentWindow

Let WebContents to be created independantly of setting up the
window tree in CastContentWindow. Allow the window tree to be
created at a later time.

R=gunsch@chromium.org
BUG=

Committed: https://crrev.com/482c153d41083ce66ff5f64cc9d61210fafd7f9d
Cr-Commit-Position: refs/heads/master@{#309577}

[gunsch, 2014-12-23 18:25:42]

lgtm % nit

https://codereview.chromium.org/823763002/diff/1/chromecast/browser/cast_cont...
File chromecast/browser/cast_content_window.cc (right):

https://codereview.chromium.org/823763002/diff/1/chromecast/browser/cast_cont...
chromecast/browser/cast_content_window.cc:89: #if defined(USE_AURA)
merge the #ifdef blocks, this is the same condition as above

[derekjchow1, 2014-12-23 18:51:29]

The CQ bit was checked by derekjchow@chromium.org

[commit-bot: I haz the power, 2014-12-23 18:52:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/823763002/20001

[commit-bot: I haz the power, 2014-12-23 19:47:36]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-12-23 19:49:52]

Patchset 2 (id:??) landed as
https://crrev.com/482c153d41083ce66ff5f64cc9d61210fafd7f9d
Cr-Commit-Position: refs/heads/master@{#309577}