Update from chromium https://crrev.com/301725/

gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc

Index: gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc
diff --git a/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc b/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc
index 1ce8303ae2dc73e9d7bd46d5e0c37e597dd4fcfe..3ceb5ff65f34b3280963e30bf260f56d46c8bec7 100644
--- a/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc
+++ b/gpu/command_buffer/tests/gl_texture_mailbox_unittest.cc
@@ -54,14 +54,14 @@ uint32 ReadTexel(GLuint id, GLint x, GLint y) {
 
 class GLTextureMailboxTest : public testing::Test {
  protected:
-  virtual void SetUp() {
+  void SetUp() override {
     gl1_.Initialize(GLManager::Options());
     GLManager::Options options;
     options.share_mailbox_manager = &gl1_;
     gl2_.Initialize(options);
   }
 
-  virtual void TearDown() {
+  void TearDown() override {
     gl1_.Destroy();
     gl2_.Destroy();
   }