[UMA] Use proper C++ objects to serialize tracked_objects across process boundaries.

base/profiler/tracked_time.h

Index: base/profiler/tracked_time.h
diff --git a/base/profiler/tracked_time.h b/base/profiler/tracked_time.h
index 5493e2068739b31ebc59c3ccf1e63ebab6364015..b3c29530535f1dba6714cfb45bee84f9b8ebfcd3 100644
--- a/base/profiler/tracked_time.h
+++ b/base/profiler/tracked_time.h
@@ -12,6 +12,7 @@
 
 namespace tracked_objects {
 
+// TODO(isherman): Shouldn't this be explicitly an int32 or something like that?

[jar (doing other things), 2012/03/21 18:19:55]

I think a change to int32 would be good.  This typedef was (as I recall) used as
an internal optimization to get closer to what we needed sooner in the call
stack.

When reading and writing these values, we do count on them being atomically
written or read (i.e., you can't get a partial read or write) on all our
platforms.  I'm careful to avoid the need for barriers and locks.  It *could* be
that to be super careful, these should be changed to atomics, with non-barrier
accesses...  but the smaller change to an explicit int32 seems like a good idea.

[Ilya Sherman, 2012/03/21 21:45:43]

Ah, looks like we are already using int32 within this header.  I've split this
bit of cleanup off into https://chromiumcodereview.appspot.com/9818004/

 typedef int DurationInt;
 
 //------------------------------------------------------------------------------