gfe-relnote: (n/a) In QuicTimeAccumulator, change a "static constexpr data member" to a "static constexpr function". No behavior change, not protected.

This caused a merge error in Chromium because QuicTimeAccumulator::kNotRunningSentinel does not have a definition. The requirement for a definition has been removed since c++17.

I could not think of a clean way to prevent this in presubmit, simply ban "static constexpr QuicTime" seems too restrictive, because some code may want to use it with a definition in .cc.

PiperOrigin-RevId: 282603664
Change-Id: Ia677ca93b851725e4509c4960c5e71fdeac5f903

quic/core/quic_time_accumulator.h

diff --git a/quic/core/quic_time_accumulator.h b/quic/core/quic_time_accumulator.h
index 772e5ff..6535d74 100644
--- a/quic/core/quic_time_accumulator.h
+++ b/quic/core/quic_time_accumulator.h
@@ -13,11 +13,14 @@
 
 // QuicTimeAccumulator accumulates elapsed times between Start(s) and Stop(s).
 class QUIC_EXPORT_PRIVATE QuicTimeAccumulator {
-  static constexpr QuicTime kNotRunningSentinel = QuicTime::Infinite();
+  // TODO(wub): Switch to a data member called kNotRunningSentinel after c++17.
+  static constexpr QuicTime NotRunningSentinel() {
+    return QuicTime::Infinite();
+  }
 
  public:
   // True if Started and not Stopped.
-  bool IsRunning() const { return last_start_time_ != kNotRunningSentinel; }
+  bool IsRunning() const { return last_start_time_ != NotRunningSentinel(); }
 
   void Start(QuicTime now) {
     DCHECK(!IsRunning());
@@ -30,7 +33,7 @@
     if (now > last_start_time_) {
       total_elapsed_ = total_elapsed_ + (now - last_start_time_);
     }
-    last_start_time_ = kNotRunningSentinel;
+    last_start_time_ = NotRunningSentinel();
     DCHECK(!IsRunning());
   }
 
@@ -58,7 +61,7 @@
   // |           |      |           |
   // |___________|  +   |___________|  =   |total_elapsed_|
   QuicTime::Delta total_elapsed_ = QuicTime::Delta::Zero();
-  QuicTime last_start_time_ = kNotRunningSentinel;
+  QuicTime last_start_time_ = NotRunningSentinel();
 };
 
 }  // namespace quic