[chromedriver] Support minidump for chrome crashes on Linux.

If minidump_path is passed in through a capability, enable minidump for crashes on Linux.

BUG=chromedriver:600

Review URL: https://codereview.chromium.org/49833003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@231932 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 231932