Add MinidumpThreadListWriter::InitializeFromSnapshot()

Add MinidumpThreadListWriter::InitializeFromSnapshot(), everything
downstream, and tests.

TEST=minidump_test
R=rsesek@chromium.org

Committed: https://chromium.googlesource.com/crashpad/crashpad/+/8248c030e25ea2b3d696b39b68cfb11e6b335673

[Mark Mentovai, 2014-10-31 17:11:09]

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

[Mark Mentovai, 2014-10-31 17:11:10]

This depends on https://codereview.chromium.org/686353004/.

[Robert Sesek, 2014-11-04 15:34:58]

https://codereview.chromium.org/693933002/diff/20001/minidump/minidump_thread...
File minidump/minidump_thread_id_map_test.cc (right):

https://codereview.chromium.org/693933002/diff/20001/minidump/minidump_thread...
minidump/minidump_thread_id_map_test.cc:56: 
Everything above this line could go in SetUp()

https://codereview.chromium.org/693933002/diff/20001/minidump/minidump_thread...
minidump/minidump_thread_id_map_test.cc:57: // A simple mapping.
…and then each of these could be a TEST().

https://codereview.chromium.org/693933002/diff/20001/snapshot/test/test_threa...
File snapshot/test/test_thread_snapshot.h (right):

https://codereview.chromium.org/693933002/diff/20001/snapshot/test/test_threa...
snapshot/test/test_thread_snapshot.h:29: //! \brief A test ModuleSnapshot that
can carry arbitrary data for testing
ThreadSnapshot

[Mark Mentovai, 2014-11-04 17:05:49]

OK, updated.

That made the test longer. It’s not worse, but I don’t know if it’s better,
either. I’m fine with it if you like it this way.

[Robert Sesek, 2014-11-04 17:34:46]

On 2014/11/04 17:05:49, Mark Mentovai wrote:
> OK, updated.
> 
> That made the test longer. It’s not worse, but I don’t know if it’s better,
> either. I’m fine with it if you like it this way.

LGTM. It's a little longer, but it makes failures significantly more clear.

[Mark Mentovai, 2014-11-04 17:36:33]

Committed patchset #4 (id:60001) manually as
8248c030e25ea2b3d696b39b68cfb11e6b335673 (presubmit successful).