Avoid base::Time::FromJavaTime() when not dealing with Java.

base/time/time.h

Index: base/time/time.h
diff --git a/base/time/time.h b/base/time/time.h
index ff8bdde3dc51e30cebc32a4e27c6a229ea79acff..27b00817338eff3012751efb59db27622cfdcd4f 100644
--- a/base/time/time.h
+++ b/base/time/time.h
@@ -492,11 +492,15 @@ class BASE_EXPORT Time : public time_internal::TimeBase<Time> {
   // 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.
+  // Consider only using this when dealing with Javascript, and using

[miu, 2017/05/10 21:43:02]

Actually, I'm trying to eliminate all uses of From/ToInternalValue()
 (interesting discussion in http://crbug.com/634507). People use them to cheat
the typing system more often than for wire-format serialization. This has and
continues to cause lots of hard-to-catch bugs, exactly what strong typing of our
time data and math is meant to prevent.

FWIW, this isn't the first time we've had issues with these "java time
conversion" functions. ToJsTime() is inconsistent with FromJsTime() because
folks decided to make the perfectly valid "0" be a representation of null only
in ToJsTime(). So, it's possible for a time math expression to correctly
evaluate to zero, but then after conversion to JS time, it'll be erroneously
interpreted as null. :-/

There was an earlier attempt to fix this that had to be rolled-back due to too
much interweaved dependence on this behavior. Nevertheless, I really want to
kill these and force the platform glue (e.g. between Blink and Chromium base) to
deal with any special conversions. Also, now that we have base::Optional, it
probably makes sense to get rid of is_null() in these time classes; which would
allow "0" to be a valid non-null result.

I'm curious: Can you point me to examples of where you found these were being
misused for serialization? I'd like to better understand the use cases (outside
of Blink<-->Chromium time type conversion).

+  // FromInternalValue()/ToInternalValue() for serialization.
   static Time FromJsTime(double ms_since_epoch);
   double ToJsTime() const;
 
   // Converts to/from Java convention for times, a number of
   // milliseconds since the epoch.
+  // Consider only using this when dealing with Java, and using
+  // FromInternalValue()/ToInternalValue() for serialization.
   static Time FromJavaTime(int64_t ms_since_epoch);
   int64_t ToJavaTime() const;