Move some parts of ProcessReader (in snapshot) to ProcessInfo (in util)

Move some parts of ProcessReader (in snapshot) to ProcessInfo (in util).

Also, move ProcessArgumentsForPID() into ProcessInfo.

This change prepares for a TaskForPID() implementation that’s capable of
operating correctly in a setuid root executable. TaskForPID() belongs in
util/mach, but for its permission checks, it must access some process
properties that were previously fetched by ProcessReader in snapshot.
util can’t depend on snapshot. The generic util-safe process information
bits (Is64Bit(), ProcessID(), ParentProcessID(), and StartTime()) are
moved from ProcessReader to ProcessInfo (in util), where the current
ProcessReader can use it (as it’s OK for snapshot to depend on util),
and the future TaskForPID() in util can also use it. ProcessInfo also
contains other methods that TaskForPID() will use, providing access to
the credentials that the target process holds. ProcessArgumentsForPID()
is related, and is also now a part of ProcessInfo.

TEST=snapshot_test, util_test
R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/6812cec67e116d9357fbefaa08af82093dce1d5d

[Mark Mentovai, 2014-11-14 21:51:47]

mark@chromium.org changed reviewers:
+ rsesek@chromium.org

[Robert Sesek, 2014-11-14 22:06:19]

https://codereview.chromium.org/727973002/diff/1/util/posix/process_info.h
File util/posix/process_info.h (right):

https://codereview.chromium.org/727973002/diff/1/util/posix/process_info.h#ne...
util/posix/process_info.h:40: 
No dtor?

https://codereview.chromium.org/727973002/diff/1/util/posix/process_info.h#ne...
util/posix/process_info.h:48: //! returns is loaded at the time Initialize() is
called or subsequently, and
This consideration then requires that the target process remain alive for the
duration of the object's lifetime, which is fine, but a little odd in a crash
reporting library.

https://codereview.chromium.org/727973002/diff/1/util/posix/process_info_test.cc
File util/posix/process_info_test.cc (right):

https://codereview.chromium.org/727973002/diff/1/util/posix/process_info_test...
util/posix/process_info_test.cc:96: int expect_argc = *_NSGetArgc();
This isn't quite POSIX-y.

[Mark Mentovai, 2014-11-14 22:16:46]

Updated.

https://codereview.chromium.org/727973002/diff/1/util/posix/process_info.h
File util/posix/process_info.h (right):

https://codereview.chromium.org/727973002/diff/1/util/posix/process_info.h#ne...
util/posix/process_info.h:48: //! returns is loaded at the time Initialize() is
called or subsequently, and
Robert Sesek wrote:
> This consideration then requires that the target process remain alive for the
> duration of the object's lifetime, which is fine, but a little odd in a crash
> reporting library.

It should be OK. A crashing process needs to be accessible for the duration that
the reporter deals with it for other purposes as well. The crashing process is
alive but not scheduleable.

I put this comment here because Arguments() doesn’t cache anything. It’s flaky
and needs to be dealt with specially by the caller, if the caller cares.

[Robert Sesek, 2014-11-14 22:51:53]

LGTM

[Mark Mentovai, 2014-11-14 22:54:46]

Committed patchset #2 (id:20001) manually as
6812cec67e116d9357fbefaa08af82093dce1d5d (presubmit successful).