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

base/profiler/scoped_tracker.cc

Index: base/profiler/scoped_tracker.cc
diff --git a/base/profiler/scoped_tracker.cc b/base/profiler/scoped_tracker.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5cd0bcae34984d1d99017ccb699d7dbe48409439
--- /dev/null
+++ b/base/profiler/scoped_tracker.cc
@@ -0,0 +1,24 @@
+// Copyright 2014 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_tracker.h"
+
+namespace tracked_objects {
+
+namespace {
+
+ScopedProfile::Mode g_scoped_profile_mode = ScopedProfile::DISABLED;
+
+}  // namespace
+
+// static
+void ScopedTracker::Enable() {
+  g_scoped_profile_mode = ScopedProfile::ENABLED;
+}
+
+ScopedTracker::ScopedTracker(const Location& location)
+    : scoped_profile_(location, g_scoped_profile_mode) {
+}
+
+}  // namespace tracked_objects