Heap profiler: use Heap::CommittedMemory to report the "total" memory size.

src/heap-profiler.cc

Index: src/heap-profiler.cc
diff --git a/src/heap-profiler.cc b/src/heap-profiler.cc
index f80c9a07bf97182386dd921e99b2c14cf521e73f..bfd378dda831e352f3c0957c8f390d8f91115cf2 100644
--- a/src/heap-profiler.cc
+++ b/src/heap-profiler.cc
@@ -603,7 +603,7 @@ static void PrintProducerStackTrace(Object* obj, void* trace) {
 void HeapProfiler::WriteSample() {
   LOG(HeapSampleBeginEvent("Heap", "allocated"));
   LOG(HeapSampleStats(
-      "Heap", "allocated", Heap::Capacity(), Heap::SizeOfObjects()));
+      "Heap", "allocated", Heap::CommittedMemory(), Heap::SizeOfObjects()));
 
   HistogramInfo info[LAST_TYPE+1];
 #define DEF_TYPE_NAME(name) info[name].set_name(#name);