Add Explicit Argument Guidance for time.h

base/time/time.h

Index: base/time/time.h
diff --git a/base/time/time.h b/base/time/time.h
index 648445f35a2394ec7bea7a5506a2dbd68ce12a67..9163795829959b847f1d73b3be88d679c392db25 100644
--- a/base/time/time.h
+++ b/base/time/time.h
@@ -25,6 +25,11 @@
 // instance. Thus, they can be efficiently passed by-value (as opposed to
 // by-reference).
 //
+// Prefer passing these classes by value:

[danakj, 2016/09/30 20:18:56]

can you combine these two comments then cuz saying it twice is weird. like..

As time classes occupy 64-bits per instance, prefer passing these classes by
value:

or something?

[robliao, 2016/09/30 20:26:29]

Done!

// All time classes are copyable, assignable, and occupy 64-bits per instance.
// As a result, prefer passing them by value:
//   void MyFunction(TimeDelta arg);
// If circumstances require, you may also pass by const reference:
//   void MyFunction(const TimeDelta& arg);  // Not preferred.

+//   void MyFunction(TimeDelta arg);
+// If circumstances require, you may also pass by const reference:
+//   void MyFunction(const TimeDelta& arg);  // Not preferred.
+//
 // Definitions of operator<< are provided to make these types work with
 // DCHECK_EQ() and other log macros. For human-readable formatting, see
 // "base/i18n/time_formatting.h".