Create TimeBase for time related classes.

src/base/platform/time.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/base/platform/time.h"
 
 #if V8_OS_POSIX
 #include <fcntl.h>  // for O_RDONLY
 #include <sys/time.h>
 #include <unistd.h>
@@ skipping 10 matching lines @@
 #include "src/base/lazy-instance.h"
 #include "src/base/win32-headers.h"
 #endif
 #include "src/base/cpu.h"
 #include "src/base/logging.h"
 #include "src/base/platform/platform.h"
 
 namespace v8 {
 namespace base {
 
+namespace time_internal {
+
+int64_t SaturatedAdd(TimeDelta delta, int64_t value) {

[fmeawad, 2016/05/04 23:34:21]

The Saturated methods does change the functionality, it is OK to include in this
CL as long as it is part of the purpose of the CL.

+  CheckedNumeric<int64_t> rv(delta.delta_);
+  rv += value;
+  return FromCheckedNumeric(rv);
+}
+
+int64_t SaturatedSub(TimeDelta delta, int64_t value) {
+  CheckedNumeric<int64_t> rv(delta.delta_);
+  rv -= value;
+  return FromCheckedNumeric(rv);
+}
+
+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 time_internal
+
+
 TimeDelta TimeDelta::FromDays(int days) {
   return TimeDelta(days * Time::kMicrosecondsPerDay);
 }
 
 
 TimeDelta TimeDelta::FromHours(int hours) {
   return TimeDelta(hours * Time::kMicrosecondsPerHour);
 }
 
 
@@ skipping 514 matching lines @@
 
 // static
 bool TimeTicks::IsHighResolutionClockWorking() {
   return true;
 }
 
 #endif  // V8_OS_WIN
 
 }  // namespace base
 }  // namespace v8