Standardize usage of virtual/override/final specifiers in sync/.

sync/internal_api/attachments/attachment_uploader_impl_unittest.cc

Index: sync/internal_api/attachments/attachment_uploader_impl_unittest.cc
diff --git a/sync/internal_api/attachments/attachment_uploader_impl_unittest.cc b/sync/internal_api/attachments/attachment_uploader_impl_unittest.cc
index 2daff32b4a188d084fb0310f827f669df6e2ceb1..4af6cd88408e67aba58d3ce2a9673d8d4597490b 100644
--- a/sync/internal_api/attachments/attachment_uploader_impl_unittest.cc
+++ b/sync/internal_api/attachments/attachment_uploader_impl_unittest.cc
@@ -194,8 +194,8 @@ class AttachmentUploaderImplTest : public testing::Test,
 
  protected:
   AttachmentUploaderImplTest();
-  virtual void SetUp();
-  virtual void TearDown();
+  void SetUp() override;
+  void TearDown() override;
 
   // Run the message loop until UploadDone has been invoked |num_uploads| times.
   void RunAndWaitFor(int num_uploads);