Linux sandbox: better APIs with /proc/ arguments

Linux sandbox: better APIs with /proc/ arguments

Unify sandbox:: APIs to always take /proc/ file descriptors
instead of /proc/self/ or /proc/self/task/.

Moreover, require |proc_fd| arguments to critical APIs rather
than rely on the caller to perform the right checks.

A descriptor to /proc is a better choice than a descriptor to
/proc/self/* because it keeps the same semantics after a fork().

BUG=312380, 457377
TBR=nasko

Committed: https://crrev.com/4d91216184b506a9f0a623919862250f65d4f3e4
Cr-Commit-Position: refs/heads/master@{#317757}

[jln (very slow on Chromium), 2015-02-24 01:45:28]

jln@chromium.org changed reviewers:
+ mdempsky@chromium.org

[jln (very slow on Chromium), 2015-02-24 01:45:38]

Matthew: PTAL!

https://codereview.chromium.org/938223004/diff/1/content/common/sandbox_linux...
File content/common/sandbox_linux/sandbox_linux.cc (right):

https://codereview.chromium.org/938223004/diff/1/content/common/sandbox_linux...
content/common/sandbox_linux/sandbox_linux.cc:81: // TODO(jln): get rid of this
ugly interface.
This will be cleaned-up when refactoring how we start the GPU sandbox.

[mdempsky, 2015-02-24 02:19:53]

lgtm

[jln (very slow on Chromium), 2015-02-24 04:59:52]

On 2015/02/24 02:19:53, mdempsky wrote:
> lgtm

Thanks Matthew!

Nasko: TBR for content/public/common/sandbox_init.h

[jln (very slow on Chromium), 2015-02-24 04:59:57]

The CQ bit was checked by jln@chromium.org

[jln (very slow on Chromium), 2015-02-24 04:59:57]

The patchset sent to the CQ was uploaded after l-g-t-m from
mdempsky@chromium.org
Link to the patchset: https://chromiumcodereview.appspot.com/938223004/#ps40001
(title: "Fix invalid proc_fd_ usage.")

[commit-bot: I haz the power, 2015-02-24 05:03:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/938223004/40001

[commit-bot: I haz the power, 2015-02-24 05:54:40]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-02-24 05:55:29]

Patchset 3 (id:??) landed as
https://crrev.com/4d91216184b506a9f0a623919862250f65d4f3e4
Cr-Commit-Position: refs/heads/master@{#317757}