Refactor CrashDump*Manager to use a shared CrashDumpObserver singleton.
CrashDumpManager watches for generated microdumps when child processes
die, and CrashMicroDumpManager is responsible for aborting the WebView
browser process. Both share similarities that can be combined, and doing
so allows us to eventually support generating a minidump and then dying
in WebView.
BUG=633979
Review-Url: https://codereview.chromium.org/2200693002
Cr-Commit-Position: refs/heads/master@{#413431}
25 files changed
