Create TimeBase for time related classes.

src/base/bits.h

Index: src/base/bits.h
diff --git a/src/base/bits.h b/src/base/bits.h
index 0e7662488428899bb8ca96677d873fcabac284db..2e6527b0548ec54f6640cc629d06c0a729959fe3 100644
--- a/src/base/bits.h
+++ b/src/base/bits.h
@@ -16,6 +16,12 @@
 
 namespace v8 {
 namespace base {
+
+namespace internal {

[jochen (gone - plz use gerrit), 2016/05/06 09:43:02]

safe_math.h has using internal::CheckedNumeric in namespace base, so why is this
needed here?

[lpy, 2016/05/06 17:23:23]

It's used in the declaration of FromCheckedNumeric.

+template <typename T>
+class CheckedNumeric;
+}
+
 namespace bits {
 
 // CountPopulation32(value) returns the number of bits set in |value|.
@@ -296,6 +302,21 @@ inline uint32_t UnsignedMod32(uint32_t lhs, uint32_t rhs) {
   return rhs ? lhs % rhs : 0u;
 }
 
+
+// Clamp |value| on overflow and underflow conditions.
+int64_t FromCheckedNumeric(const internal::CheckedNumeric<int64_t> value);
+
+
+// SignedSaturatedAdd64(lhs, rhs) adds |lhs| and |rhs|,
+// checks and returns the result.
+int64_t SignedSaturatedAdd64(int64_t lhs, int64_t rhs);
+
+
+// SignedSaturatedSub64(lhs, rhs) substracts |lhs| by |rhs|,
+// checks and returns the result.
+int64_t SignedSaturatedSub64(int64_t lhs, int64_t rhs);
+
+
 }  // namespace bits
 }  // namespace base
 }  // namespace v8