Simplify allocation tracker API

src/heap-snapshot-generator.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 734 matching lines @@
   delete *snapshot_ptr;
 }
 
 
 HeapSnapshotsCollection::~HeapSnapshotsCollection() {
   delete allocation_tracker_;
   snapshots_.Iterate(DeleteHeapSnapshot);
 }
 
 
-void HeapSnapshotsCollection::StartHeapObjectsTracking() {
+void HeapSnapshotsCollection::StartHeapObjectsTracking(bool track_allocations) {
   ids_.UpdateHeapObjectsMap();
-  if (allocation_tracker_ == NULL) {
+  ASSERT(allocation_tracker_ == NULL);
+  if (track_allocations) {
     allocation_tracker_ = new AllocationTracker(&ids_, names());
   }
 }
 
 
 void HeapSnapshotsCollection::StopHeapObjectsTracking() {
   ids_.StopHeapObjectsTracking();
   if (allocation_tracker_ != NULL) {
     delete allocation_tracker_;
     allocation_tracker_ = NULL;
@@ skipping 2294 matching lines @@
   writer_->AddString("\"<dummy>\"");
   for (int i = 1; i < sorted_strings.length(); ++i) {
     writer_->AddCharacter(',');
     SerializeString(sorted_strings[i]);
     if (writer_->aborted()) return;
   }
 }
 
 
 } }  // namespace v8::internal