heap: Add MarkBailOutObjects scope to ThreadHeap::AdvanceMarking

Bug: 986235
Change-Id: I4e1556dfba5f8b99cf488fcaacbcddc9d5564ad9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2066843Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Omer Katz <omerkatz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#743524}

third_party/blink/renderer/platform/heap/heap.cc

@@ -347,6 +347,9 @@ bool ThreadHeap::AdvanceMarking(MarkingVisitor* visitor,
       if (!finished)
         break;
 
+      {
+        ThreadHeapStatsCollector::EnabledScope bailout_scope(
+            stats_collector(), ThreadHeapStatsCollector::kMarkBailOutObjects);
         finished = DrainWorklistWithDeadline(
             deadline, not_safe_to_concurrently_trace_worklist_.get(),
             [visitor](const MarkingItem& item) {
@@ -355,6 +358,7 @@ bool ThreadHeap::AdvanceMarking(MarkingVisitor* visitor,
             WorklistTaskId::MutatorThread);
         if (!finished)
           break;
+      }
 
       finished = DrainWorklistWithDeadline(
           deadline, marking_worklist_.get(),

third_party/blink/renderer/platform/heap/heap_stats_collector.h

@@ -54,6 +54,7 @@ class PLATFORM_EXPORT ThreadHeapStatsObserver {
   V(InvokePreFinalizers)              \
   V(LazySweepInIdle)                  \
   V(LazySweepOnAllocation)            \
+  V(MarkBailOutObjects)               \
   V(MarkInvokeEphemeronCallbacks)     \
   V(MarkProcessWorklist)              \
   V(MarkNotFullyConstructedObjects)   \