Convert Media Galleries to use base::File

Unfortunately, this brings in changes to webkit/browser/fileapi, and once
that changes, a lot of files have to be updated.

The bright side is that most of the collateral changes are just trivial
renaming of PlatformFileError -> File::Error and PlatformFileInfo ->
File::Info

BUG=322664

Review URL: https://codereview.chromium.org/145303002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247301 0039d316-1c4b-4281-b951-d872f2087c98
247 files changed