Make stack sampling profiler sample beyond startup.

base/time/time.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.
 
 // Time represents an absolute point in coordinated universal time (UTC),
 // internally represented as microseconds (s/1,000,000) since the Windows epoch
 // (1601-01-01 00:00:00 UTC). System-dependent clock interface routines are
 // defined in time_PLATFORM.cc. Note that values for Time may skew and jump
 // around as the operating system makes adjustments to synchronize (e.g., with
 // NTP servers). Thus, client code that uses the Time class must account for
@@ skipping 392 matching lines @@
     return us_ >= other.us_;
   }
 
   // Converts an integer value representing TimeClass to a class. This is used
   // when deserializing a |TimeClass| structure, using a value known to be
   // compatible. It is not provided as a constructor because the integer type
   // may be unclear from the perspective of a caller.
   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_;
 };
 
 }  // namespace time_internal
 
 template<class TimeClass>
 inline TimeClass operator+(TimeDelta delta, TimeClass t) {
   return t + delta;
@@ skipping 309 matching lines @@
   // The underlying clock used to generate new TimeTicks.
   enum class Clock {
     FUCHSIA_MX_CLOCK_MONOTONIC,
     LINUX_CLOCK_MONOTONIC,
     IOS_CF_ABSOLUTE_TIME_MINUS_KERN_BOOTTIME,
     MAC_MACH_ABSOLUTE_TIME,
     WIN_QPC,
     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
   // as coarse as ~15.6ms. Otherwise, the resolution should be no worse than one
   // microsecond.
   static TimeTicks Now();
 
   // Returns true if the high resolution clock is working on this system and
   // Now() will return high resolution values. Note that, on systems where the
   // high resolution clock works but is deemed inefficient, the low resolution
@@ skipping 128 matching lines @@
   static void WaitUntilInitializedWin();
 #endif
 };
 
 // For logging use only.
 BASE_EXPORT std::ostream& operator<<(std::ostream& os, ThreadTicks time_ticks);
 
 }  // namespace base
 
 #endif  // BASE_TIME_TIME_H_