Reverts third_party/protobuf: Update to HEAD (f52e188fe4)

third_party/protobuf/src/google/protobuf/duration.proto

 // Protocol Buffers - Google's data interchange format
 // Copyright 2008 Google Inc.  All rights reserved.
 // https://developers.google.com/protocol-buffers/
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
@@ skipping 15 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 syntax = "proto3";
 
 package google.protobuf;
 
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
-option cc_enable_arenas = true;
 option go_package = "github.com/golang/protobuf/ptypes/duration";
 option java_package = "com.google.protobuf";
 option java_outer_classname = "DurationProto";
 option java_multiple_files = true;
+option java_generate_equals_and_hash = true;
 option objc_class_prefix = "GPB";
 
 // A Duration represents a signed, fixed-length span of time represented
 // as a count of seconds and fractions of seconds at nanosecond
 // resolution. It is independent of any calendar and concepts like "day"
 // or "month". It is related to Timestamp in that the difference between
 // two Timestamp values is a Duration and it can be added or subtracted
 // from a Timestamp. Range is approximately +-10,000 years.
 //
 // Example 1: Compute Duration from two Timestamps in pseudo code.
@@ skipping 23 matching lines @@
 //     end.nanos = start.nanos + duration.nanos;
 //
 //     if (end.nanos < 0) {
 //       end.seconds -= 1;
 //       end.nanos += 1000000000;
 //     } else if (end.nanos >= 1000000000) {
 //       end.seconds += 1;
 //       end.nanos -= 1000000000;
 //     }
 //
-// Example 3: Compute Duration from datetime.timedelta in Python.
-//
-//     td = datetime.timedelta(days=3, minutes=10)
-//     duration = Duration()
-//     duration.FromTimedelta(td)
-//
 //
 message Duration {
 
   // Signed seconds of the span of time. Must be from -315,576,000,000
   // to +315,576,000,000 inclusive.
   int64 seconds = 1;
 
   // Signed fractions of a second at nanosecond resolution of the span
   // of time. Durations less than one second are represented with a 0
   // `seconds` field and a positive or negative `nanos` field. For durations
   // of one second or more, a non-zero value for the `nanos` field must be
   // of the same sign as the `seconds` field. Must be from -999,999,999
   // to +999,999,999 inclusive.
   int32 nanos = 2;
 }