Adding api to get last gc object statistics for chrome://tracing.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index a1e2e1671e42c0e7072e05fa194688400a41e296..110d60deb9e6634789d55468b5cf675df5bc67c3 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -6439,5 +6439,35 @@ void Heap::CheckpointObjectStats() {
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
+
+
+const char* Heap::GetObjectTypeName(size_t index) {
+  if (index > OBJECT_STATS_COUNT)

[ulan, 2015/05/06 12:46:02]

index >= OBJECT_STATS_COUNT

[ssid, 2015/05/07 13:53:03]

Done.

+    return nullptr;
+
+  switch (static_cast<int>(index)) {
+#define ADJUST_LAST_TIME_OBJECT_COUNT(name) \

[ulan, 2015/05/06 12:46:02]

The name "ADJUST_LAST_TIME_OBJECT_COUNT" is confusing here. Maybe
"COMPARE_AND_RETURN_NAME" or "CASE_NAME" ?

[ssid, 2015/05/07 13:53:03]

Done.

+  case name:                                \
+    return #name;
+    INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
+#undef ADJUST_LAST_TIME_OBJECT_COUNT
+#define ADJUST_LAST_TIME_OBJECT_COUNT(name)   \
+  case FIRST_CODE_KIND_SUB_TYPE + Code::name: \
+    return "CODE_TYPE_" #name;
+    CODE_KIND_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
+#undef ADJUST_LAST_TIME_OBJECT_COUNT
+#define ADJUST_LAST_TIME_OBJECT_COUNT(name) \
+  case FIRST_FIXED_ARRAY_SUB_TYPE + name:   \
+    return "FIXED_ARRAY_" #name;
+    FIXED_ARRAY_SUB_INSTANCE_TYPE_LIST(ADJUST_LAST_TIME_OBJECT_COUNT)
+#undef ADJUST_LAST_TIME_OBJECT_COUNT
+#define ADJUST_LAST_TIME_OBJECT_COUNT(name)                                    \
+  case FIRST_CODE_AGE_SUB_TYPE + Code::k##name##CodeAge - Code::kFirstCodeAge: \
+    return "CODE_AGE_" #name;
+    CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
+#undef ADJUST_LAST_TIME_OBJECT_COUNT
+  }
+  return nullptr;
+}
 }
 }  // namespace v8::internal