Expose TickSample and its APIs in v8-profiler.h

src/profiler/cpu-profiler-inl.h

Index: src/profiler/cpu-profiler-inl.h
diff --git a/src/profiler/cpu-profiler-inl.h b/src/profiler/cpu-profiler-inl.h
index d8c9c909c292390b9a288a1812824115cc4ec6c4..50acb76a33b2c4ed69e865776fd1d0223a561790 100644
--- a/src/profiler/cpu-profiler-inl.h
+++ b/src/profiler/cpu-profiler-inl.h
@@ -71,6 +71,10 @@ TickSample* ProfilerEventsProcessor::StartTickSample() {
 
 
 void ProfilerEventsProcessor::FinishTickSample() {
+  TickSampleEventRecord* evt = ticks_buffer_.CurrentEnqueue();
+  evt->timestamp = evt->sample.pc == nullptr

[alph, 2016/06/29 19:39:09]

It's not its business. FinishTickSample should not update the record. Also I'd
rename it to CommitTickSample

[lpy, 2016/06/29 20:17:39]

Since I remove the timestamp from TickSample, I think it makes sense that when
FinishTickSample gets called, it stamps the timestamp on the record since it
knows the current ticksample in record has been written.

Why CommitTickSample? Since we already have another function named
StarTickSample, should we keep it as a pair? Or rename StartTickSample to
RequestTickSample?

+                       ? base::TimeTicks()
+                       : base::TimeTicks::HighResolutionNow();
   ticks_buffer_.FinishEnqueue();
 }