Windows: Automatically associate file types with Chrome apps.

Currently only works if --enable-apps-file-associations is on.

The Chrome app appears on the "Open with" menu and "Choose default
program" dialog for files of any type mentioned in the app's manifest.
If there is no existing app associated with the file type, the Chrome
app becomes the default handler.

Upon app installation, creates a copy of the app_shim executable to
serve as a portable and uniquely named way to run the app. Any file
types mentioned in the file_handlers section of the app manifest are
associated with the shim.

BUG=130455

Review URL: https://codereview.chromium.org/181493011

Cr-Commit-Position: refs/heads/master@{#302755}
1 file changed