[profiler] Implement POC Sampling Heap Profiler

src/profiler/heap-profiler.h

Index: src/profiler/heap-profiler.h
diff --git a/src/profiler/heap-profiler.h b/src/profiler/heap-profiler.h
index 9a04e83af4b0ca2f3725f8a10fcdabd322ba41b7..74539ae142786557bc3229e870b66f076192ed78 100644
--- a/src/profiler/heap-profiler.h
+++ b/src/profiler/heap-profiler.h
@@ -16,6 +16,7 @@ namespace internal {
 class AllocationTracker;
 class HeapObjectsMap;
 class HeapSnapshot;
+class SamplingHeapProfiler;
 class StringsStorage;
 
 class HeapProfiler {
@@ -29,6 +30,10 @@ class HeapProfiler {
       v8::ActivityControl* control,
       v8::HeapProfiler::ObjectNameResolver* resolver);
 
+  bool StartSamplingHeapProfiler(uint64_t sample_interval, int stack_depth);
+  void StopSamplingHeapProfiler();
+  AllocationProfile* GetAllocationProfile();
+
   void StartHeapObjectsTracking(bool track_allocations);
   void StopHeapObjectsTracking();
   AllocationTracker* allocation_tracker() const {
@@ -79,6 +84,7 @@ class HeapProfiler {
   base::SmartPointer<AllocationTracker> allocation_tracker_;
   bool is_tracking_object_moves_;
   base::Mutex profiler_mutex_;
+  base::SmartPointer<SamplingHeapProfiler> sampling_heap_profiler_;
 };
 
 }  // namespace internal