[Tizen] Use DesktopRootWindowHostX11 in chromium, instead of DesktopRootWindowHostTizenX11.

Rationale
1. Bugs are created when we rebase to upstream because of confliction.
2. Hard to follow up upstream changes.
3. We need to change DesktopRootWindowHostX11 pretty smaller than we expected.

BUG=https://crosswalk-project.org/jira/browse/XWALK-12
Merge pull request #1025 from ds-hwang/rootwindow

[Tizen] Use DesktopRootWindowHostX11 in chromium, instead of DesktopRootWindowHostTizenX11.