[heap] Add histogram timers for incremental marking start and finalization event.

src/heap/heap.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/heap.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/bits.h"
 #include "src/base/once.h"
@@ skipping 774 matching lines @@
   scavenge_job_->ScheduleIdleTaskIfNeeded(this, bytes_allocated);
 }
 
 
 void Heap::FinalizeIncrementalMarking(const char* gc_reason) {
   if (FLAG_trace_incremental_marking) {
     PrintF("[IncrementalMarking] (%s).\n", gc_reason);
   }
 
   GCTracer::Scope gc_scope(tracer(), GCTracer::Scope::MC_INCREMENTAL_FINALIZE);
+  HistogramTimerScope incremental_marking_scope(
+      isolate()->counters()->gc_incremental_marking_finalize());
 
   {
     GCCallbacksScope scope(this);
     if (scope.CheckReenter()) {
       AllowHeapAllocation allow_allocation;
       GCTracer::Scope scope(tracer(), GCTracer::Scope::EXTERNAL);
       VMState<EXTERNAL> state(isolate_);
       HandleScope handle_scope(isolate_);
       CallGCPrologueCallbacks(kGCTypeIncrementalMarking, kNoGCCallbackFlags);
     }
@@ skipping 5378 matching lines @@
 }
 
 
 // static
 int Heap::GetStaticVisitorIdForMap(Map* map) {
   return StaticVisitorBase::GetVisitorId(map);
 }
 
 }  // namespace internal
 }  // namespace v8