Update {virtual,override,final} to follow C++11 style in media, round 2.

The Google style guide states that only one of {virtual,override,final}
should be used for each declaration, since override implies virtual and
final implies both virtual and override.

This patch was automatically generated with a ChromeOS build using a
variation of https://codereview.chromium.org/598073004.

BUG=417463

Review URL: https://codereview.chromium.org/870743003

Cr-Commit-Position: refs/heads/master@{#312798}

media/video/capture/linux/video_capture_device_chromeos.cc

@@ -41,14 +41,12 @@ class VideoCaptureDeviceChromeOS::ScreenObserverDelegate
  private:
   friend class base::RefCountedThreadSafe<ScreenObserverDelegate>;
 
-  virtual ~ScreenObserverDelegate() {
-    DCHECK(!capture_device_);
-  }
+  ~ScreenObserverDelegate() override { DCHECK(!capture_device_); }
 
-  virtual void OnDisplayAdded(const gfx::Display& /*new_display*/) override {}
-  virtual void OnDisplayRemoved(const gfx::Display& /*old_display*/) override {}
-  virtual void OnDisplayMetricsChanged(const gfx::Display& display,
-                                       uint32_t metrics) override {
+  void OnDisplayAdded(const gfx::Display& /*new_display*/) override {}
+  void OnDisplayRemoved(const gfx::Display& /*old_display*/) override {}
+  void OnDisplayMetricsChanged(const gfx::Display& display,
+                               uint32_t metrics) override {
     DCHECK(ui_task_runner_->BelongsToCurrentThread());
     if (!(metrics & DISPLAY_METRIC_ROTATION))
       return;

media/video/capture/linux/video_capture_device_chromeos.h

@@ -21,7 +21,7 @@ class VideoCaptureDeviceChromeOS : public VideoCaptureDeviceLinux {
   explicit VideoCaptureDeviceChromeOS(
       scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
       const Name& device_name);
-  virtual ~VideoCaptureDeviceChromeOS();
+  ~VideoCaptureDeviceChromeOS() override;
 
  private:
   class ScreenObserverDelegate;