Mojom parser: Use Encoder.SetDeterministic(true) for stable encodings.

mojom/mojom_parser/serialization/serialization_test.go

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package serialization
 
 import (
         "fmt"
         "mojo/public/go/bindings"
         "mojom/mojom_parser/generated/mojom_files"
@@ skipping 991 matching lines @@
                         }
                 }
 
                 // Serialize
                 bytes, _, err := serialize(descriptor, false, c.lineAndcolumnNumbers, false)
                 if err != nil {
                         t.Errorf("Serialization error for %s: %s", c.fileName, err.Error())
                         continue
                 }
 
+                // Serialize again and check for consistency.
+                bytes2, _, err := serialize(descriptor, false, c.lineAndcolumnNumbers, false)
+                if err != nil {
+                        t.Errorf("Serialization error for %s: %s", c.fileName, err.Error())
+                        continue
+                }
+
+                if !reflect.DeepEqual(bytes, bytes2) {
+                        t.Errorf("Inconsistent serialization for %s:\nbytes=%v\nbytes2=%v\n",
+                                c.fileName, bytes, bytes2)
+                        continue
+                }
+
                 // Deserialize
                 decoder := bindings.NewDecoder(bytes, nil)
                 fileGraph := mojom_files.MojomFileGraph{}
                 fileGraph.Decode(decoder)
 
                 // Compare
                 if err := compareTwoGoObjects(c.expectedGraph, &fileGraph); err != nil {
                         t.Errorf("%s:\n%s", c.fileName, err.Error())
                         continue
                 }
@@ skipping 1036 matching lines @@
                         }
                         return fmt.Errorf("*****\nexpected=\n*****\n%q\n*****\nactual=\n*****\n%q\n*****\n"+
                                 "match failed at position %d: expected=\n*****\n%q\n******\nactual=\n*****\n%q\n******\n",
                                 expectedString, actualString, diffPos, mismatchExpected, mismatchActual)
                 } else {
                         return fmt.Errorf("expected != actual but the two printed equal.")
                 }
         }
         return nil
 }