Provide nanoseconds precision for base::PlatformFileInfo on POSIX

base/time.h

Index: base/time.h
diff --git a/base/time.h b/base/time.h
index 9c20b548b474031e190c806c6aef2a5ad27a3c1c..e722122d2113d7adfcf054ba072825cf5f0cb01e 100644
--- a/base/time.h
+++ b/base/time.h
@@ -286,6 +286,14 @@ class BASE_EXPORT Time {
   static Time FromDoubleT(double dt);
   double ToDoubleT() const;
 
+#if defined(OS_POSIX)
+  // Converts the timespec structure to time. MacOS X 10.8.3 (and tentatively,
+  // earlier versions) will have the |ts|'s tv_nsec component zeroed out,
+  // having a 1 second resolution, which agrees with
+  // https://developer.apple.com/legacy/library/#technotes/tn/tn1150.html#HFSPlusDates.
+  static Time FromTimeSpec(const timespec& ts);
+#endif
+
   // Converts to/from the Javascript convention for times, a number of
   // milliseconds since the epoch:
   // https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/getTime.