Create TimeBase for time related classes.

src/base/bits.cc

Index: src/base/bits.cc
diff --git a/src/base/bits.cc b/src/base/bits.cc
index 74d747fc9059f135cc2986b9b73f6ce473391534..1666229d5ccec1121ad56a3783d3d8022810591e 100644
--- a/src/base/bits.cc
+++ b/src/base/bits.cc
@@ -48,6 +48,21 @@ int32_t SignedMod32(int32_t lhs, int32_t rhs) {
   return lhs % rhs;
 }
 
+
+int64_t FromCheckedNumeric(const CheckedNumeric<int64_t> value) {
+  if (value.IsValid())
+    return value.ValueUnsafe();
+
+  // We could return max/min but we don't really expose what the maximum delta
+  // is. Instead, return max/(-max), which is something that clients can reason
+  // about.
+  // TODO(rvargas) crbug.com/332611: don't use internal values.
+  int64_t limit = std::numeric_limits<int64_t>::max();
+  if (value.validity() == internal::RANGE_UNDERFLOW)
+    limit = -limit;
+  return value.ValueOrDefault(limit);
+}
+
 }  // namespace bits
 }  // namespace base
 }  // namespace v8