Add: check exploded time is properly converted

base/time/time.h

Index: base/time/time.h
diff --git a/base/time/time.h b/base/time/time.h
index 9fce71b581e4ca27c216e31cb40ab78b867760ea..ede6ebd6a756d7dc4efa6c0612a1f1f266f7539d 100644
--- a/base/time/time.h
+++ b/base/time/time.h
@@ -420,6 +420,7 @@ class BASE_EXPORT Time : public time_internal::TimeBase<Time> {
     // respective ranges. A 'true' return value does not guarantee the
     // Exploded value can be successfully converted to a Time value.
     bool HasValidValues() const;
+    bool operator!=(const Exploded& rhs);
   };
 
   // Contains the NULL time. Use Time::Now() to get the current time.
@@ -522,6 +523,20 @@ class BASE_EXPORT Time : public time_internal::TimeBase<Time> {
     return FromExploded(true, exploded);
   }
 
+  // Converts an exploded structure representing either the local time or UTC
+  // into a Time class.
+  // This is a transition to a new format, where the converted time is set to
+  // |time| and FromUTCExploded, FromLocalExploded and FromExploded return true
+  // on success or false on failure. For example, FromExploded can fail when
+  // 31st of a month is set on a 28-30 day month, which results in 1st day of
+  // the next month.
+  static bool FromUTCExploded(const Exploded& exploded, Time& time) {

[mmenke, 2016/05/20 19:44:56]

Per Google C++ style guide, non-const refs are forbidden.  These should be
passing in a Time*.

[maksims (do not use this acc), 2016/05/24 09:14:21]

Done.

+    return FromExploded(false, exploded, time);
+  }
+  static bool FromLocalExploded(const Exploded& exploded, Time& time) {

[mmenke, 2016/05/20 19:44:56]

These two should use WARN_UNUSED_RESULT.

[maksims (do not use this acc), 2016/05/24 09:14:21]

Done.

+    return FromExploded(true, exploded, time);
+  }

[mmenke, 2016/05/20 19:44:56]

Is the plan to replace calls to the old methods with calls to these?

[maksims (do not use this acc), 2016/05/24 09:14:21]

Yes, I would like to do so.

+
   // Converts a string representation of time to a Time object.
   // An example of a time string which is converted is as below:-
   // "Tue, 15 Nov 1994 12:45:26 GMT". If the timezone is not specified
@@ -563,6 +578,13 @@ class BASE_EXPORT Time : public time_internal::TimeBase<Time> {
   // |is_local = true| or UTC |is_local = false|.
   static Time FromExploded(bool is_local, const Exploded& exploded);

[mmenke, 2016/05/20 19:44:56]

If we're going to keep the old methods around (Permanently?  Temporarily?), we
should probably still get rid of this method, and make the two old public
functions wrap the new FromExploded function.

Also, since the new methods have WARN_UNUSED_RESULT in the new methods, you'll
need to use ignore_result on the calls in the two old methods to the new
FromExploded method.

[maksims (do not use this acc), 2016/05/24 09:14:21]

Done.

 
+  // Unexplodes a given time assuming the source is either local time
+  // |is_local = true| or UTC |is_local = false|.
+  // This is a transition to a newer form. Function returns false on failure
+  // and sets |time| to Time(0). Otherwise returns true and sets |time| to
+  // non-exploded time.
+  static bool FromExploded(bool is_local, const Exploded& exploded, Time& time);

[mmenke, 2016/05/20 19:44:56]

WARN_UNUSED_RESULT

[maksims (do not use this acc), 2016/05/24 09:14:21]

Done.

+
   // Converts a string representation of time to a Time object.
   // An example of a time string which is converted is as below:-
   // "Tue, 15 Nov 1994 12:45:26 GMT". If the timezone is not specified