Remove V8.External traces due to its high overhead

src/vm-state-inl.h

 // Copyright 2010 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.
 
 #ifndef V8_VM_STATE_INL_H_
 #define V8_VM_STATE_INL_H_
 
 #include "src/vm-state.h"
 #include "src/log.h"
 #include "src/simulator.h"
@@ skipping 22 matching lines @@
     default:
       UNREACHABLE();
       return NULL;
   }
 }
 
 
 template <StateTag Tag>
 VMState<Tag>::VMState(Isolate* isolate)
     : isolate_(isolate), previous_tag_(isolate->current_vm_state()) {
-  if (previous_tag_ != EXTERNAL && Tag == EXTERNAL) {
-    if (FLAG_log_timer_events) {
-      LOG(isolate_, TimerEvent(Logger::START, TimerEventExternal::name()));
-    }
-    TRACE_EVENT_BEGIN0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.External");
+  if (FLAG_log_timer_events && previous_tag_ != EXTERNAL && Tag == EXTERNAL) {
+    LOG(isolate_, TimerEvent(Logger::START, TimerEventExternal::name()));
   }
   isolate_->set_current_vm_state(Tag);
 }
 
 
 template <StateTag Tag>
 VMState<Tag>::~VMState() {
-  if (previous_tag_ != EXTERNAL && Tag == EXTERNAL) {
-    if (FLAG_log_timer_events) {
-      LOG(isolate_, TimerEvent(Logger::END, TimerEventExternal::name()));
-    }
-    TRACE_EVENT_END0(TRACE_DISABLED_BY_DEFAULT("v8"), "V8.External");
+  if (FLAG_log_timer_events && previous_tag_ != EXTERNAL && Tag == EXTERNAL) {
+    LOG(isolate_, TimerEvent(Logger::END, TimerEventExternal::name()));
   }
   isolate_->set_current_vm_state(previous_tag_);
 }
 
 ExternalCallbackScope::ExternalCallbackScope(Isolate* isolate, Address callback)
     : isolate_(isolate),
       callback_(callback),
       previous_scope_(isolate->external_callback_scope()),
       timer_(&isolate->counters()->runtime_call_stats()->ExternalCallback,
              isolate->counters()->runtime_call_stats()->current_timer()) {
@@ skipping 19 matching lines @@
 #else
   return reinterpret_cast<Address>(this);
 #endif
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_VM_STATE_INL_H_