Add relaunch into ASH and desktop support for Chrome on Windows 7.

This is on similar lines as Windows 8. The difference being launching into ASH on Windows 8 launches
ASH into Windows 8 metro environment.

Reused the existing tunneling we have via delegate_execute to ensure that the calling process is terminated
before launching the browser into the other environment.

Removed the erstshile Open Ash Desktop and Close Ash Desktop menu options as they are no longer needed and they
don't work correctly anyways.

BUG=356475

Review URL: https://codereview.chromium.org/498573003

Cr-Commit-Position: refs/heads/master@{#292464}
18 files changed