Standardize usage of virtual/override/final in mojo/

mojo/services/native_viewport/platform_viewport_mac.mm

Index: mojo/services/native_viewport/platform_viewport_mac.mm
diff --git a/mojo/services/native_viewport/platform_viewport_mac.mm b/mojo/services/native_viewport/platform_viewport_mac.mm
index 40bee95f5154520d32154572132c32460ecc64c2..a74b6baf5e2c1b24f2299e8f98b39007c655cc3d 100644
--- a/mojo/services/native_viewport/platform_viewport_mac.mm
+++ b/mojo/services/native_viewport/platform_viewport_mac.mm
@@ -20,14 +20,14 @@ class PlatformViewportMac : public PlatformViewport {
         window_(nil) {
   }
 
-  virtual ~PlatformViewportMac() {
+  ~PlatformViewportMac() override {
     [window_ orderOut:nil];
     [window_ close];
   }
 
  private:
   // Overridden from PlatformViewport:
-  virtual void Init(const gfx::Rect& bounds) override {
+  void Init(const gfx::Rect& bounds) override {
     [NSApplication sharedApplication];
 
     rect_ = bounds;
@@ -40,34 +40,22 @@ class PlatformViewportMac : public PlatformViewport {
     delegate_->OnBoundsChanged(rect_);
   }
 
-  virtual void Show() override {
-    [window_ orderFront:nil];
-  }
+  void Show() override { [window_ orderFront:nil]; }
 
-  virtual void Hide() override {
-    [window_ orderOut:nil];
-  }
+  void Hide() override { [window_ orderOut:nil]; }
 
-  virtual void Close() override {
+  void Close() override {
     // TODO(beng): perform this in response to NSWindow destruction.
     delegate_->OnDestroyed();
   }
 
-  virtual gfx::Size GetSize() override {
-    return rect_.size();
-  }
+  gfx::Size GetSize() override { return rect_.size(); }
 
-  virtual void SetBounds(const gfx::Rect& bounds) override {
-    NOTIMPLEMENTED();
-  }
+  void SetBounds(const gfx::Rect& bounds) override { NOTIMPLEMENTED(); }
 
-  virtual void SetCapture() override {
-    NOTIMPLEMENTED();
-  }
+  void SetCapture() override { NOTIMPLEMENTED(); }
 
-  virtual void ReleaseCapture() override {
-    NOTIMPLEMENTED();
-  }
+  void ReleaseCapture() override { NOTIMPLEMENTED(); }
 
   Delegate* delegate_;
   NSWindow* window_;