Relanding https://codereview.chromium.org/197713005/, was reverted in
r256945. Turned out this CL was not the culprit. Hence relanding it.

TBR=sergeyu@chromium.org

Review URL: https://codereview.chromium.org/195893016

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257000 0039d316-1c4b-4281-b951-d872f2087c98
Implement ScopedFD in terms of ScopedGeneric.

Move to a new file base/files/scoped_file.h. I will also add ScopedFILE to here (currently in file_util.h) later.

I think there is a crash in the old code in content/browser/zygote_host/zygote_host_impl_linux.cc that this patch should fix. The old ScopedFD took the address of something in a vector that is being modified.

I removed SafeScopedFD from content/common/sandbox_linux/sandbox_linux.cc since base's ScopedFD not CHECKs on close failure (this is a more recent addition).

BUG=
R=agl@chromium.org, viettrungluu@chromium.org

Review URL: https://codereview.chromium.org/191673003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257001 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 257001
and bumping once more

Review URL: https://codereview.chromium.org/196473020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257004 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 257004