Updates handling of handlers in the image writer.

The Image Writer ran into some errors where Windows has been updating
the partition table of the disk between the writing and verification
stages.  The key to preventing this seems to be to hold the handles open
between the two stages.

This changes the utility-process portion of the image writer to hold
open handles until closed or the file paths change.  This means that a
write-and-verify operation on the same files will keep the file handles
open.

Initially the idea was to dismount the volumes to discourage windows
from writing, and this is something we wanted to add anyway, so this
adds that as well.

Note that the dismounting is called from the image_writer_handler so
that the write and verify methods remain unit-testable on fake files.

BUG=352442

Review URL: https://codereview.chromium.org/253543003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@268719 0039d316-1c4b-4281-b951-d872f2087c98

0 files changed, 0 insertions, 0 deletions