Fixed the bug that Drive doesn't appear on Files App on epehmeral mode.

Fixed the bug that Drive doesn't appear on Files App on epehmeral mode.

The CL https://codereview.chromium.org/2006503002 assumed file extended attributes and file attributes are available in GCache/v1/files to distinguish removable Drive caches. However, it is not true for ephemral mode, in which tmpfs is used to mount user directory. As a result in ephemeral mode initialization of file caches always fails and thus Drive folder doesn't appear in Files App.
This CL fixes the issue by not touching file attributes if underlying filesystem doesn't support it. We compute the availability by checking if the errno is ENOTSUP after xattr() is called.

BUG=650268
TEST=Using link, the following are confirmed on ephemeral mode.
- Drive appears in Files App.
- Copy & paste between Download and Drive, Drive and Drive are successfully done.
- Pin/unpin on Drive works.
- /var/log/ui/ui.LATEST doesn't report any error in file_cache.cc .

patch from issue 2412063002 at patchset 80001 (http://crrev.com/2412063002#ps80001)

(cherry picked from commit abb32757690fc60983520918cdeba1b77fdc2d11)

Committed: https://chromium.googlesource.com/chromium/src/+/f4b5d9146363e4eec2e41a6d59f21cea4466e0b0

[oka, 2016-10-14 14:18:48]

Description was changed from

==========
Fixed the bug that Drive doesn't appear on Files App on epehmeral mode.

The CL https://codereview.chromium.org/2006503002 assumed file extended
attributes and file attributes are available in GCache/v1/files to distinguish
removable Drive caches. However, it is not true for ephemral mode, in which
tmpfs is used to mount user directory. As a result in ephemeral mode
initialization of file caches always fails and thus Drive folder doesn't appear
in Files App.
This CL fixes the issue by not touching file attributes if underlying filesystem
doesn't support it. We compute the availability by checking if the errno is
ENOTSUP after xattr() is called.

BUG=650268
TEST=Using link, the following are confirmed on ephemeral mode.
- Drive appears in Files App.
- Copy & paste between Download and Drive, Drive and Drive are successfully
done.
- Pin/unpin on Drive works.
- /var/log/ui/ui.LATEST doesn't report any error in file_cache.cc .

patch from issue 2412063002 at patchset 80001
(http://crrev.com/2412063002#ps80001)

(cherry picked from commit abb32757690fc60983520918cdeba1b77fdc2d11)
==========

to

==========
Fixed the bug that Drive doesn't appear on Files App on epehmeral mode.

The CL https://codereview.chromium.org/2006503002 assumed file extended
attributes and file attributes are available in GCache/v1/files to distinguish
removable Drive caches. However, it is not true for ephemral mode, in which
tmpfs is used to mount user directory. As a result in ephemeral mode
initialization of file caches always fails and thus Drive folder doesn't appear
in Files App.
This CL fixes the issue by not touching file attributes if underlying filesystem
doesn't support it. We compute the availability by checking if the errno is
ENOTSUP after xattr() is called.

BUG=650268
TEST=Using link, the following are confirmed on ephemeral mode.
- Drive appears in Files App.
- Copy & paste between Download and Drive, Drive and Drive are successfully
done.
- Pin/unpin on Drive works.
- /var/log/ui/ui.LATEST doesn't report any error in file_cache.cc .

patch from issue 2412063002 at patchset 80001
(http://crrev.com/2412063002#ps80001)

(cherry picked from commit abb32757690fc60983520918cdeba1b77fdc2d11)

Committed:
https://chromium.googlesource.com/chromium/src/+/f4b5d9146363e4eec2e41a6d59f2...
==========

[oka, 2016-10-14 14:18:50]

Committed patchset #1 (id:1) manually as
f4b5d9146363e4eec2e41a6d59f21cea4466e0b0.