Perform smaller marking steps incrementally in idle notification.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 8986087486995ac660de31f0d164b0a03ebc37f4..3e8923987b9966581fdb8cc2de9fba48623dd0d3 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -4489,12 +4489,17 @@ bool Heap::IdleNotification(double deadline_in_seconds) {
       if (incremental_marking()->IsStopped()) {
         incremental_marking()->Start();
       }
-      incremental_marking()->Step(action.parameter,
-                                  IncrementalMarking::NO_GC_VIA_STACK_GUARD,
-                                  IncrementalMarking::FORCE_MARKING,
-                                  IncrementalMarking::DO_NOT_FORCE_COMPLETION);
-      double remaining_idle_time_in_ms =
-          deadline_in_ms - MonotonicallyIncreasingTimeInMs();
+      double remaining_idle_time_in_ms = 0.0;
+      do {
+        incremental_marking()->Step(
+            action.parameter, IncrementalMarking::NO_GC_VIA_STACK_GUARD,
+            IncrementalMarking::FORCE_MARKING,
+            IncrementalMarking::DO_NOT_FORCE_COMPLETION);
+        remaining_idle_time_in_ms =
+            deadline_in_ms - MonotonicallyIncreasingTimeInMs();
+      } while (remaining_idle_time_in_ms >= 2 &&

[jochen (gone - plz use gerrit), 2014/12/02 10:30:31]

maybe 2.0 * kIncrementalMarkingStepTimeInMs?

[Hannes Payer (out of office), 2014/12/02 10:37:54]

Done.

+               !incremental_marking()->IsComplete() &&
+               !mark_compact_collector_.marking_deque()->IsEmpty());
       if (remaining_idle_time_in_ms > 0.0) {
         TryFinalizeIdleIncrementalMarking(
             remaining_idle_time_in_ms, heap_state.size_of_objects,