Fix segfault when interpreting bad debug_file
Fix segfault when interpreting bad debug_file

BUG=chromium:661037

Change-Id: Ia4da0bd9787c232a6a199cfdfccfbed60c2515c2
Reviewed-on: https://chromium-review.googlesource.com/450090
Reviewed-by: Joshua Peraza <f5809a5e35ec7e1bd0e25cb0a0b68bb433cf6f17@chromium.org>

bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad,bittorrent/breakpad