Revert 222470 "Use an X event loop in the GPU process on Linux." This is to

Revert 222470 "Use an X event loop in the GPU process on Linux." This is to
check if it adds an unexpected dependency on libxi6.

> Use an X event loop in the GPU process on Linux.
>
> In future patches, X windows will be created in the GPU
> process, and events sent to these windows will need to
> be forwarded to their parent windows.
>
> Linux uses GTK as the default UI event loop type, but
> GTK is not in the GPU process, so the X11 event loop
> type is used instead.
>
> BUG=145600
>
> Review URL: https://chromiumcodereview.appspot.com/23477050

TBR=ccameron@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=222589

[Noam Samuel, 2013-09-11 17:52:45]

Committed patchset #1 manually as r222589.