Change to calculate the real NTP in TimeTicks.

base/time/time.cc

Index: base/time/time.cc
diff --git a/base/time/time.cc b/base/time/time.cc
index a9e4b1cf90aa61c031feaa05f52a01111090f431..9f3c53d6695b1e8b4960dc4911c761dff3b7aa56 100644
--- a/base/time/time.cc
+++ b/base/time/time.cc
@@ -8,6 +8,7 @@
 #include <ostream>
 
 #include "base/float_util.h"
+#include "base/lazy_instance.h"
 #include "base/logging.h"
 #include "base/third_party/nspr/prtime.h"
 #include "base/third_party/nspr/prtypes.h"
@@ -189,6 +190,29 @@ bool Time::FromStringInternal(const char* time_string,
   return true;
 }
 
+// Local helper class to hold the conversion from Time to TickTime at the
+// time of the Unix epoch.
+class UnixEpochSingleton {
+ public:
+  UnixEpochSingleton()
+      : unix_epoch_(TimeTicks::Now() - (Time::Now() - Time::UnixEpoch())) {}
+
+  TimeTicks unix_epoch() const { return unix_epoch_; }
+
+ private:
+  const TimeTicks unix_epoch_;
+
+  DISALLOW_COPY_AND_ASSIGN(UnixEpochSingleton);
+};
+
+static LazyInstance<UnixEpochSingleton>::Leaky
+    leaky_unix_epoch_singleton_instance = LAZY_INSTANCE_INITIALIZER;
+
+// Static
+TimeTicks TimeTicks::UnixEpoch() {
+  return leaky_unix_epoch_singleton_instance.Get().unix_epoch();
+}
+
 // Time::Exploded -------------------------------------------------------------
 
 inline bool is_in_range(int value, int lo, int hi) {