Add some instrumentation to catch the source of a potential double-free.

Add some instrumentation to catch the source of a potential double-free.

It saves the stack trace where initial deletion happened from. In the case where the deletion was initiated by DeleteSoon(), we will show the stacktrace for the caller of that function (rather than the actual deletion stacktrace from running the task).

BUG=94179
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=98540

[eroman, 2011-08-26 19:14:27]

I tested this on a local Release build but base::debug::StackTrace() doesn't
seem to be working. Not sure why, so I am leaving the StackTrace code in here on
the off-chance that it works from the canary (since if it works will be super
useful).

Even if StackTrace doesn't work, this instrumentation should still yield some
useful data from the "liveness_token", showing if it definitely was a
double-free.

[darin (slow to review), 2011-08-26 19:25:53]

LGTM... good luck!!

[eroman, 2011-08-26 20:42:05]

FYI: the reason base::debug::StackTrace() is not working from release builds is
due to frame pointer optimization (it gets confused and can't walk the stack
correctly). I'll follow up about that separately, since we can improve things a
bit by disabling FPO inside some key frames.

[commit-bot: I haz the power, 2011-08-27 02:41:15]

Change committed as 98540