Support tracking of IPC messages as tasks in profiler

Support tracking of IPC messages as tasks in profiler

Also started to do more cleanup, including creating
a base/profiler directory, and moving parts of the
over-sized tracked_objects.* into that directory.

r=rtenneti
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=108752

[jar (doing other things), 2011-11-04 21:53:25]

This was all focused around profiling the incoming IPC messages.  Most
everything else was moving code to better support this additional activity.

I'll have to be careful to watch the perf bots when I land, to be sure I don't
impact them.... but I think IPC is relatively expensive, and the Tallying of
data in profiling is pretty minimal.

[ramant (doing other things), 2011-11-04 22:14:05]

lgtm