[heap] Add VMState to IncrementalMarking observer

src/heap/incremental-marking.cc

Index: src/heap/incremental-marking.cc
diff --git a/src/heap/incremental-marking.cc b/src/heap/incremental-marking.cc
index b5d023512f2c62609862ea02c2c84af4753fe9b8..a9a71cfb6367f7d9ef5882db7bf02f245501b625 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -18,10 +18,19 @@
 #include "src/tracing/trace-event.h"
 #include "src/v8.h"
 #include "src/visitors.h"
+#include "src/vm-state-inl.h"
 
 namespace v8 {
 namespace internal {
 
+void IncrementalMarking::Observer::Step(int bytes_allocated, Address, size_t) {
+  VMState<GC> state(incremental_marking_.heap()->isolate());
+  RuntimeCallTimerScope runtime_timer(
+      incremental_marking_.heap()->isolate(),
+      &RuntimeCallStats::GC_IncrementalMarkingObserver);
+  incremental_marking_.AdvanceIncrementalMarkingOnAllocation();
+}
+
 IncrementalMarking::IncrementalMarking(Heap* heap)
     : heap_(heap),
       marking_deque_(nullptr),