Make stack sampling profiler sample beyond startup.

base/time/time.h

Index: base/time/time.h
diff --git a/base/time/time.h b/base/time/time.h
index f231cf7010081cefd8e4a78c0e22d8292036aa85..dd3b2b87312ab9c1dc50e817afb38058f1cb0667 100644
--- a/base/time/time.h
+++ b/base/time/time.h
@@ -410,7 +410,7 @@ class TimeBase {
   static TimeClass FromInternalValue(int64_t us) { return TimeClass(us); }
 
  protected:
-  explicit TimeBase(int64_t us) : us_(us) {}
+  constexpr explicit TimeBase(int64_t us) : us_(us) {}
 
   // Time value in a microsecond timebase.
   int64_t us_;
@@ -740,8 +740,7 @@ class BASE_EXPORT TimeTicks : public time_internal::TimeBase<TimeTicks> {
     WIN_ROLLOVER_PROTECTED_TIME_GET_TIME
   };
 
-  TimeTicks() : TimeBase(0) {
-  }
+  constexpr TimeTicks() : TimeBase(0) {}
 
   // Platform-dependent tick count representing "right now." When
   // IsHighResolution() returns false, the resolution of the clock could be