Add fast ELF Symbolizer to memory_inspector.

This CL introduces a multiprocess, pipelined and asynchronous ELF
symbolizer (based on addr2line) which gives honor to a bulkly workstation
when symbolizing large batches of symbols.

BUG=340294,339059

Review URL: https://codereview.chromium.org/167893009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252963 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252963