Update {virtual,override} to follow C++11 style in ppapi.

ppapi/shared_impl/resource_tracker_unittest.cc

Index: ppapi/shared_impl/resource_tracker_unittest.cc
diff --git a/ppapi/shared_impl/resource_tracker_unittest.cc b/ppapi/shared_impl/resource_tracker_unittest.cc
index 31c61b3f412d4fe3d6417c891fd8eb1f93a8c15d..a8fac3b139f818ebabc3120920464dcfe588259b 100644
--- a/ppapi/shared_impl/resource_tracker_unittest.cc
+++ b/ppapi/shared_impl/resource_tracker_unittest.cc
@@ -23,12 +23,12 @@ class MyMockResource : public Resource {
   MyMockResource(PP_Instance instance) : Resource(OBJECT_IS_IMPL, instance) {
     mock_resource_alive_count++;
   }
-  virtual ~MyMockResource() { mock_resource_alive_count--; }
+  ~MyMockResource() override { mock_resource_alive_count--; }
 
-  virtual void LastPluginRefWasDeleted() override {
+  void LastPluginRefWasDeleted() override {
     last_plugin_ref_was_deleted_count++;
   }
-  virtual void InstanceWasDeleted() override { instance_was_deleted_count++; }
+  void InstanceWasDeleted() override { instance_was_deleted_count++; }
 };
 
 }  // namespace
@@ -38,12 +38,12 @@ class ResourceTrackerTest : public testing::Test {
   ResourceTrackerTest() {}
 
   // Test implementation.
-  virtual void SetUp() override {
+  void SetUp() override {
     ASSERT_EQ(0, mock_resource_alive_count);
     last_plugin_ref_was_deleted_count = 0;
     instance_was_deleted_count = 0;
   }
-  virtual void TearDown() override {}
+  void TearDown() override {}
 
   ResourceTracker& resource_tracker() { return *globals_.GetResourceTracker(); }