GitLab

This implements the crash handler companion to the launcher in https://codereview.chromium.org/2596463002/. The handler parses the command line as created by the launcher. After this, it can write a minidump with MinidumpWriteDump, then augment it with Crashpad metadata and massage such that Crashpad can parse it.
After this, the dump is dropped into the Crashpad database for eventual upload.

BUG=678959

Review-Url: https://codereview.chromium.org/2611393002
Cr-Commit-Position: refs/heads/master@{#443249}