Some more virtual/override updates.

(These are mostly fixes to things that derive from testing::Test, which
are missed for some reason.)

R=sky@chromium.org

Review URL: https://codereview.chromium.org/644963004
diff --git a/mojo/shell/child_process_host_unittest.cc b/mojo/shell/child_process_host_unittest.cc
index 2cd24db..123cbfb 100644
--- a/mojo/shell/child_process_host_unittest.cc
+++ b/mojo/shell/child_process_host_unittest.cc
@@ -21,7 +21,7 @@
 class TestChildProcessHostDelegate : public ChildProcessHost::Delegate {
  public:
   TestChildProcessHostDelegate() {}
-  virtual ~TestChildProcessHostDelegate() {}
+  ~TestChildProcessHostDelegate() {}
   void WillStart() override {
     VLOG(2) << "TestChildProcessHostDelegate::WillStart()";
   }