Start incremental marking in idle time handler only if it is worthwhile.

src/heap/gc-idle-time-handler.cc

Index: src/heap/gc-idle-time-handler.cc
diff --git a/src/heap/gc-idle-time-handler.cc b/src/heap/gc-idle-time-handler.cc
index a2e08b28c514e1c08c0c394a9100c8da6150897d..90f916e2f45a025b056eee843de8d6de4556d7c2 100644
--- a/src/heap/gc-idle-time-handler.cc
+++ b/src/heap/gc-idle-time-handler.cc
@@ -46,22 +46,20 @@ size_t GCIdleTimeHandler::EstimateMarkCompactTime(
 
 
 GCIdleTimeAction GCIdleTimeHandler::Compute(int idle_time_in_ms,
-                                            int contexts_disposed,
-                                            size_t size_of_objects,
-                                            bool incremental_marking_stopped,
+                                            HeapState heap_state,
                                             GCTracer* gc_tracer) {
   if (IsIdleRoundFinished()) {
-    if (EnoughGarbageSinceLastIdleRound() || contexts_disposed > 0) {
+    if (EnoughGarbageSinceLastIdleRound() || heap_state.contexts_disposed > 0) {
       StartIdleRound();
     } else {
       return GCIdleTimeAction::Nothing();
     }
   }
-  if (incremental_marking_stopped) {
+  if (heap_state.incremental_marking_stopped) {
     size_t speed =
         static_cast<size_t>(gc_tracer->MarkCompactSpeedInBytesPerMillisecond());
-    if (idle_time_in_ms >=
-        static_cast<int>(EstimateMarkCompactTime(size_of_objects, speed))) {
+    if (idle_time_in_ms >= static_cast<int>(EstimateMarkCompactTime(
+                               heap_state.size_of_objects, speed))) {
       // If there are no more than two GCs left in this idle round and we are
       // allowed to do a full GC, then make those GCs full in order to compact
       // the code space.
@@ -69,10 +67,14 @@ GCIdleTimeAction GCIdleTimeHandler::Compute(int idle_time_in_ms,
       // can get rid of this special case and always start incremental marking.
       int remaining_mark_sweeps =
           kMaxMarkCompactsInIdleRound - mark_compacts_since_idle_round_started_;
-      if (contexts_disposed > 0 || remaining_mark_sweeps <= 2) {
+      if (heap_state.contexts_disposed > 0 || remaining_mark_sweeps <= 2 ||
+          !heap_state.can_start_incremental_marking) {
         return GCIdleTimeAction::FullGC();
       }
     }
+    if (!heap_state.can_start_incremental_marking) {
+      return GCIdleTimeAction::Nothing();
+    }
   }
   intptr_t speed = gc_tracer->IncrementalMarkingSpeedInBytesPerMillisecond();
   size_t step_size =