Revert of When we switch tabs in chrome, the tab being switched away from gets hidden/shown/hidden.

Revert of When we switch tabs in chrome, the tab being switched away from gets hidden/shown/hidden. (patchset #14 id:260001 of https://codereview.chromium.org/564553002/)

Reason for revert:
This seems to cause memory leaks in WebViewUnitTest.TestWebViewAttachDetachWebContents on Linux(ASan/LSan) and ChromiumOS(ASan/LSan)

http://build.chromium.org/p/chromium.memory/builders/Linux%20ASan%20LSan%20Tests%20%282%29/builds/7468

Original issue's description:
> When we switch tabs in chrome, the tab being switched away from gets hidden/shown/hidden.
>
> This occurs in the NativeViewHostAura::NativeViewDetaching code path where we first remove the
> clipping window which is the intermediate parent of the web contents view. The clipping window
> is hidden which causes the RWHVA::Hide function to get called which initiates the hiding sequence.
> Then the web contents view is reparented to the main view which is still visible. Now the RWHVA::Show
> function is called which initiates the show sequence. Eventually the main view is hidden, which then
> initiates the hide sequence.
>
> Addressed this with the following changes.
> 1. WebView::AttachWebContents and WebView::DetachWebContents
>    now show and hide the webcontents native view. The
>    WebContents is shown and hidden as before in
>    WebContentsNativeViewAura::OnWindowVisibilityChanged.
>
> 2. Removed the WebContentsNativeViewAura::OnWindowParentChanged function.
>    This function was present to show and hide the webcontents if the window was visible.
>    This should not be needed with the change in #1 above.
>
> 3. Added a new file webview_unittest.cc. This contains the unittest WebViewUnitTest.TestWebViewAttachDetachWebContents
>    This is run as part of unit_tests.exe.
>
> BUG=412989
> R=sky
>
> Committed: https://crrev.com/99941773a742f62892fc9aad1a1ebfb7cc967164
> Cr-Commit-Position: refs/heads/master@{#294962}

TBR=sky@chromium.org,ananta@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=412989
Committed: https://crrev.com/e467a7139b660a5fddc72012cdc6628de9fa9f25
Cr-Commit-Position: refs/heads/master@{#295020}

[nhiroki, 2014-09-16 06:23:46]

Created Revert of When we switch tabs in chrome, the tab being switched away
from gets hidden/shown/hidden.

[commit-bot: I haz the power, 2014-09-16 06:24:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/577533003/1

[commit-bot: I haz the power, 2014-09-16 06:26:05]

Committed patchset #1 (id:1) as 734782a55f1cf8065614e781b4d6720ac152022a

[commit-bot: I haz the power, 2014-09-16 06:27:17]

Patchset 1 (id:??) landed as
https://crrev.com/e467a7139b660a5fddc72012cdc6628de9fa9f25
Cr-Commit-Position: refs/heads/master@{#295020}