Remove FLAG_finalize_marking_incrementally for simplicity.

BUG=

Review URL: https://codereview.chromium.org/1496253002

Cr-Commit-Position: refs/heads/master@{#32602}

src/flag-definitions.h

@@ -670,8 +670,6 @@ DEFINE_BOOL(age_code, true,
             "track un-executed functions to age code and flush only "
             "old code (required for code flushing)")
 DEFINE_BOOL(incremental_marking, true, "use incremental marking")
-DEFINE_BOOL(finalize_marking_incrementally, true,
-            "finalize marking in incremental steps")
 DEFINE_INT(min_progress_during_incremental_marking_finalization, 32,
            "keep finalizing incremental marking as long as we discover at "
            "least this many unmarked objects")

src/heap/heap.cc

@@ -762,11 +762,8 @@ void Heap::HandleGCRequest() {
       IncrementalMarking::COMPLETE_MARKING) {
     CollectAllGarbage(current_gc_flags_, "GC interrupt",
                       current_gc_callback_flags_);
-    return;
-  }
-  DCHECK(FLAG_finalize_marking_incrementally);
-  if (incremental_marking()->IsMarking() &&
-      !incremental_marking()->finalize_marking_completed()) {
+  } else if (incremental_marking()->IsMarking() &&
+             !incremental_marking()->finalize_marking_completed()) {
     FinalizeIncrementalMarking("GC interrupt: finalize incremental marking");
   }
 }
@@ -4032,8 +4029,7 @@ void Heap::ReduceNewSpaceSize() {
 
 
 void Heap::FinalizeIncrementalMarkingIfComplete(const char* comment) {
-  if (FLAG_finalize_marking_incrementally &&
-      incremental_marking()->IsMarking() &&
+  if (incremental_marking()->IsMarking() &&
       (incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
        (!incremental_marking()->finalize_marking_completed() &&
         mark_compact_collector()->marking_deque()->IsEmpty()))) {
@@ -4050,12 +4046,11 @@ bool Heap::TryFinalizeIdleIncrementalMarking(double idle_time_in_ms) {
   size_t final_incremental_mark_compact_speed_in_bytes_per_ms =
       static_cast<size_t>(
           tracer()->FinalIncrementalMarkCompactSpeedInBytesPerMillisecond());
-  if (FLAG_finalize_marking_incrementally &&
-      (incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
-       (!incremental_marking()->finalize_marking_completed() &&
-        mark_compact_collector()->marking_deque()->IsEmpty() &&
-        gc_idle_time_handler_->ShouldDoOverApproximateWeakClosure(
-            static_cast<size_t>(idle_time_in_ms))))) {
+  if (incremental_marking()->IsReadyToOverApproximateWeakClosure() ||
+      (!incremental_marking()->finalize_marking_completed() &&
+       mark_compact_collector()->marking_deque()->IsEmpty() &&
+       gc_idle_time_handler_->ShouldDoOverApproximateWeakClosure(
+           static_cast<size_t>(idle_time_in_ms)))) {
     FinalizeIncrementalMarking(
         "Idle notification: finalize incremental marking");
     return true;

src/heap/incremental-marking.cc

@@ -624,7 +624,6 @@ void IncrementalMarking::StartMarking() {
 
 
 void IncrementalMarking::MarkRoots() {
-  DCHECK(FLAG_finalize_marking_incrementally);
   DCHECK(!finalize_marking_completed_);
   DCHECK(IsMarking());
 
@@ -634,7 +633,6 @@ void IncrementalMarking::MarkRoots() {
 
 
 void IncrementalMarking::MarkObjectGroups() {
-  DCHECK(FLAG_finalize_marking_incrementally);
   DCHECK(!finalize_marking_completed_);
   DCHECK(IsMarking());
 
@@ -648,7 +646,6 @@ void IncrementalMarking::MarkObjectGroups() {
 
 
 void IncrementalMarking::ProcessWeakCells() {
-  DCHECK(FLAG_finalize_marking_incrementally);
   DCHECK(!finalize_marking_completed_);
   DCHECK(IsMarking());
 
@@ -686,7 +683,6 @@ void IncrementalMarking::ProcessWeakCells() {
 
 
 void IncrementalMarking::FinalizeIncrementally() {
-  DCHECK(FLAG_finalize_marking_incrementally);
   DCHECK(!finalize_marking_completed_);
   DCHECK(IsMarking());
 
@@ -941,7 +937,6 @@ void IncrementalMarking::Finalize() {
 
 
 void IncrementalMarking::FinalizeMarking(CompletionAction action) {
-  DCHECK(FLAG_finalize_marking_incrementally);
   DCHECK(!finalize_marking_completed_);
   if (FLAG_trace_incremental_marking) {
     PrintF(
@@ -1154,8 +1149,7 @@ intptr_t IncrementalMarking::Step(intptr_t allocated_bytes,
       if (heap_->mark_compact_collector()->marking_deque()->IsEmpty()) {
         if (completion == FORCE_COMPLETION ||
             IsIdleMarkingDelayCounterLimitReached()) {
-          if (FLAG_finalize_marking_incrementally &&
-              !finalize_marking_completed_) {
+          if (!finalize_marking_completed_) {
             FinalizeMarking(action);
           } else {
             MarkingComplete(action);