Update from chromium https://crrev.com/301725/

base/profiler/scoped_profile.cc

 // Copyright (c) 2011 The Chromium 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 "base/profiler/scoped_profile.h"
 
 #include "base/location.h"
 #include "base/tracked_objects.h"
 
 
 namespace tracked_objects {
 
 
 ScopedProfile::ScopedProfile(const Location& location)
     : birth_(ThreadData::TallyABirthIfActive(location)) {
+  if (!birth_)
+    return;
+
   ThreadData::PrepareForStartOfRun(birth_);
+  stopwatch_.Start();
+}
+
+ScopedProfile::ScopedProfile(const Location& location, Mode mode)
+    : birth_(NULL) {
+  if (mode == DISABLED)
+    return;
+
+  birth_ = ThreadData::TallyABirthIfActive(location);
+  if (!birth_)
+    return;
+
+  ThreadData::PrepareForStartOfRun(birth_);
+  stopwatch_.Start();
 }
 
 ScopedProfile::~ScopedProfile() {
-  StopClockAndTally();
-}
-
-void ScopedProfile::StopClockAndTally() {
-  stopwatch_.Stop();
-
   if (!birth_)
     return;
+
+  stopwatch_.Stop();
   ThreadData::TallyRunInAScopedRegionIfTracking(birth_, stopwatch_);
-  birth_ = NULL;
 }
 
 }  // namespace tracked_objects