Clean up VMState a little bit.

src/vm-state-inl.h

 // Copyright 2010 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 29 matching lines @@
 // VMState construction and popped by destruction.
 //
 inline const char* StateToString(StateTag state) {
   switch (state) {
     case JS:
       return "JS";
     case GC:
       return "GC";
     case COMPILER:
       return "COMPILER";
-    case PARALLEL_COMPILER:
-      return "PARALLEL_COMPILER";
     case OTHER:
       return "OTHER";
     case EXTERNAL:
       return "EXTERNAL";
     default:
       UNREACHABLE();
       return NULL;
   }
 }
 
 
-VMState::VMState(Isolate* isolate, StateTag tag)
+template <StateTag Tag>
+VMState<Tag>::VMState(Isolate* isolate)
     : isolate_(isolate), previous_tag_(isolate->current_vm_state()) {
-  if (FLAG_log_state_changes) {
-    LOG(isolate, UncheckedStringEvent("Entering", StateToString(tag)));
-    LOG(isolate, UncheckedStringEvent("From", StateToString(previous_tag_)));
+  if (FLAG_log_timer_events && previous_tag_ != EXTERNAL && Tag == EXTERNAL) {
+    LOG(isolate_,
+        TimerEvent(Logger::START, Logger::TimerEventScope::v8_external));
   }
-
-  if (FLAG_log_timer_events && previous_tag_ != EXTERNAL && tag == EXTERNAL) {
-    LOG(isolate_, EnterExternal());
-  }
-
-  isolate_->SetCurrentVMState(tag);
+  isolate_->set_current_vm_state(Tag);
 }
 
 
-VMState::~VMState() {
-  if (FLAG_log_state_changes) {
+template <StateTag Tag>
+VMState<Tag>::~VMState() {
+  if (FLAG_log_timer_events && previous_tag_ != EXTERNAL && Tag == EXTERNAL) {
     LOG(isolate_,
-        UncheckedStringEvent("Leaving",
-                              StateToString(isolate_->current_vm_state())));
-    LOG(isolate_,
-        UncheckedStringEvent("To", StateToString(previous_tag_)));
+        TimerEvent(Logger::END, Logger::TimerEventScope::v8_external));
   }
-
-  if (FLAG_log_timer_events &&
-      previous_tag_ != EXTERNAL && isolate_->current_vm_state() == EXTERNAL) {
-    LOG(isolate_, LeaveExternal());
-  }
-
-  isolate_->SetCurrentVMState(previous_tag_);
+  isolate_->set_current_vm_state(previous_tag_);
 }
 
 
 ExternalCallbackScope::ExternalCallbackScope(Isolate* isolate, Address callback)
     : isolate_(isolate), previous_callback_(isolate->external_callback()) {
   isolate_->set_external_callback(callback);
 }
 
 ExternalCallbackScope::~ExternalCallbackScope() {
   isolate_->set_external_callback(previous_callback_);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_VM_STATE_INL_H_