[fsp] Pass more detailed errors to the providing extension.
Before, many methods were returning a simple bool, which was later converted
to a generic SECURITY error code (if false).
This patch converts such bools to base::File::Error, so we can convey the
specific error code.
Note, that base::File::Error is used to pass all error codes within the File
System API implementation, even if it's not really related to files. We may
want to introduce our own type in the future.
TEST=unit_tests, browser_tests: *FileSystemProvider*
BUG=248427
Review URL: https://codereview.chromium.org/703123003
Cr-Commit-Position: refs/heads/master@{#303413}
23 files changed
