[profiler] Implement POC Sampling Heap Profiler

src/profiler/heap-profiler.cc

Index: src/profiler/heap-profiler.cc
diff --git a/src/profiler/heap-profiler.cc b/src/profiler/heap-profiler.cc
index 4403e5d6c9c965cea6851644097200f90b6a64e8..a26e90fe6c6cfeb0003a7824d3fdef8046405d09 100644
--- a/src/profiler/heap-profiler.cc
+++ b/src/profiler/heap-profiler.cc
@@ -5,9 +5,12 @@
 #include "src/profiler/heap-profiler.h"
 
 #include "src/api.h"
+#include "src/base/utils/random-number-generator.h"
 #include "src/debug/debug.h"
+#include "src/frames-inl.h"
 #include "src/profiler/allocation-tracker.h"
 #include "src/profiler/heap-snapshot-generator-inl.h"
+#include "src/profiler/sampling-heap-profiler.h"
 
 namespace v8 {
 namespace internal {
@@ -84,6 +87,31 @@ HeapSnapshot* HeapProfiler::TakeSnapshot(
 }
 
 
+bool HeapProfiler::StartSamplingHeapProfiler(uint64_t sample_interval,
+                                             int stack_depth) {
+  if (sampling_heap_profiler_.get()) {
+    return false;
+  }
+  sampling_heap_profiler_.Reset(new SamplingHeapProfiler(
+      heap(), names_.get(), sample_interval, stack_depth));
+  return true;
+}
+
+
+void HeapProfiler::StopSamplingHeapProfiler() {
+  sampling_heap_profiler_.Reset(nullptr);
+}
+
+
+v8::AllocationProfile HeapProfiler::GetAllocationProfile() {
+  if (sampling_heap_profiler_.get()) {
+    return sampling_heap_profiler_->GetAllocationProfile();
+  } else {
+    return v8::AllocationProfile();  // Empty profile.
+  }
+}
+
+
 void HeapProfiler::StartHeapObjectsTracking(bool track_allocations) {
   ids_->UpdateHeapObjectsMap();
   is_tracking_object_moves_ = true;