Implement tagging of profiler log event blocks.

Implement tagging of profiler log event blocks.

This change allows to associate integer tags with blocks of profiler
log events, and repeat calls to 'ResumeProfiler' / 'PauseProfiler' in
order to establsh nested (not necessary properly nested) blocks. By
supporting this, we will be able to match WebInspector's CPU profiler
abilities in DevTools.

I also refactored some testing code.

Committed: http://code.google.com/p/v8/source/detail?r=3889

[Søren Thygesen Gjesse, 2010-02-17 13:18:26]

LGTM

http://codereview.chromium.org/619004/diff/1/6
File src/log.cc (right):

http://codereview.chromium.org/619004/diff/1/6#newcode1172
src/log.cc:1172: if (--cpu_profiler_nesting_ == 0) {
Maybe make a note that these counters can be both positive and negative.

[mnaganov (inactive), 2010-02-17 13:22:50]

http://codereview.chromium.org/619004/diff/1/6
File src/log.cc (right):

http://codereview.chromium.org/619004/diff/1/6#newcode1172
src/log.cc:1172: if (--cpu_profiler_nesting_ == 0) {
On 2010/02/17 13:18:26, Søren Gjesse wrote:
> Maybe make a note that these counters can be both positive and negative.

Done.