Fix a bug with mojom imports where 2 imports with the same namespace would

mojo/public/bindings/tests/sample_service.mojom

 // Copyright 2013 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.
 
 import "sample_import.mojom"
+import "sample_import2.mojom"
 
 module sample {
 
 enum BarType {
   BAR_VERTICAL = 1 << 0,
   BAR_HORIZONTAL = (1 << 1) + 0,
   BAR_BOTH = BAR_VERTICAL | BAR_HORIZONTAL,
   BAR_INVALID
 };
 
@@ skipping 24 matching lines @@
   int32 age @2;
   string[] names = ["Jim"] @1;
   int32 height = 6*12 @3;
 };
 
 struct DefaultsTest {
   sample.DefaultsTestInner[] people = [{32, ["Bob", "Bobby"]}] @1;
   uint8[] data = [1, 2, 3] @2;
   imported.Point point = {7, 15} @3;
   int32[] shape_masks = [1 << imported.SHAPE_RECTANGLE] @4;
+  imported.Thing thing = {imported.SHAPE_RECTANGLE, imported.COLOR_RED};
 };
 
 interface Port {
   void PostMessage(string message_text @0) @0;
 };
 
 [Peer=ServiceClient]
 interface Service {
   enum BazOptions {
     BAZ_REGULAR = 0,
     BAZ_EXTRA
   };
   void Frobinate(Foo foo @0, int32 baz @1, Port port @2) @0;
 };
 
 [Peer=Service]
 interface ServiceClient {
   void DidFrobinate(int32 result @0) @0;
 };
 
 }