[profiler] Implement POC Sampling Heap Profiler

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index 8ff302f8d82702fa40c471082186a28ed91c8e90..9f7b070cce5abb9a341db456511d1f3fd8d90787 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -8281,6 +8281,28 @@ SnapshotObjectId HeapProfiler::GetHeapStats(OutputStream* stream,
 }
 
 
+bool HeapProfiler::StartSamplingHeapProfiler(uint64_t sample_interval,
+                                             int stack_depth) {
+  return reinterpret_cast<i::HeapProfiler*>(this)
+      ->StartSamplingHeapProfiler(sample_interval, stack_depth);
+}
+
+
+void HeapProfiler::StopSamplingHeapProfiler() {
+  reinterpret_cast<i::HeapProfiler*>(this)->StopSamplingHeapProfiler();
+}
+
+
+AllocationProfile HeapProfiler::GetAllocationProfile() {
+  return reinterpret_cast<i::HeapProfiler*>(this)->GetAllocationProfile();
+}
+
+
+AllocationProfile::Node* AllocationProfile::GetRootNode() {
+  return nodes.size() == 0 ? nullptr : &nodes.front();
+}
+
+
 void HeapProfiler::DeleteAllHeapSnapshots() {
   reinterpret_cast<i::HeapProfiler*>(this)->DeleteAllSnapshots();
 }