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

base/tracked_objects.h

 // Copyright (c) 2012 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.
 
 #ifndef BASE_TRACKED_OBJECTS_H_
 #define BASE_TRACKED_OBJECTS_H_
 
 #include <map>
 #include <set>
 #include <stack>
@@ skipping 691 matching lines @@
 // be subtracted from the current most nested task's run time. Stopwatches
 // coordinate with the stopwatches in which they are nested to avoid
 // double-counting nested tasks run times.
 
 class BASE_EXPORT TaskStopwatch {
  public:
   // Starts the stopwatch.
   TaskStopwatch();
   ~TaskStopwatch();
 
+  // Starts stopwatch.
+  void Start();
+
   // Stops stopwatch.
   void Stop();
 
   // Returns the start time.
   TrackedTime StartTime() const;
 
   // Task's duration is calculated as the wallclock duration between starting
   // and stopping this stopwatch, minus the wallclock durations of any other
   // instances that are immediately nested in this one, started and stopped on
   // this thread during that period.
@@ skipping 15 matching lines @@
   // Sum of wallclock durations of all stopwatches that were directly nested in
   // this one.
   int32 excluded_duration_ms_;
 
   // Stopwatch which was running on our thread when this stopwatch was started.
   // That preexisting stopwatch must be adjusted to the exclude the wallclock
   // duration of this stopwatch.
   TaskStopwatch* parent_;
 
 #if DCHECK_IS_ON
-  // State of the stopwatch. Stopwatch is first constructed in a running state,
-  // then stopped, then destructed.
-  enum {
-    RUNNING,
-    STOPPED
-  } state_;
+  // State of the stopwatch. Stopwatch is first constructed in a created state
+  // state, then is optionally started/stopped, then destructed.
+  enum { CREATED, RUNNING, STOPPED } state_;
 
   // Currently running stopwatch that is directly nested in this one, if such
   // stopwatch exists. NULL otherwise.
   TaskStopwatch* child_;
 #endif
 };
 
 //------------------------------------------------------------------------------
 // A snapshotted representation of a (parent, child) task pair, for tracking
 // hierarchical profiles.
@@ skipping 18 matching lines @@
   ~ProcessDataSnapshot();
 
   std::vector<TaskSnapshot> tasks;
   std::vector<ParentChildPairSnapshot> descendants;
   int process_id;
 };
 
 }  // namespace tracked_objects
 
 #endif  // BASE_TRACKED_OBJECTS_H_