Enforce marking "override" for functions overriding Blink.

BUG=535367
TEST=it all stays working
CQ_INCLUDE_TRYBOTS=tryserver.blink:linux_blink_rel
R=thakis@chromium.org
TBR=ben@chromium.org

Committed: https://crrev.com/32ff552858e014d454ce8b181f5aca1dfcf8f8fd
Cr-Commit-Position: refs/heads/master@{#363482}

Review URL: https://codereview.chromium.org/1370923002 .

Cr-Commit-Position: refs/heads/master@{#363564}

20 files changed, 127 insertions, 133 deletions

diff --git a/android_webview/renderer/aw_content_settings_client.h b/android_webview/renderer/aw_content_settings_client.h
index 5d44551..90a9479 100644
--- a/android_webview/renderer/aw_content_settings_client.h
+++ b/android_webview/renderer/aw_content_settings_client.h
@@ -20,14 +20,14 @@ class AwContentSettingsClient : public content::RenderFrameObserver,
   ~AwContentSettingsClient() override;
 
   // blink::WebContentSettingsClient implementation.
-  virtual bool allowDisplayingInsecureContent(
+  bool allowDisplayingInsecureContent(
       bool enabled_per_settings,
       const blink::WebSecurityOrigin& origin,
-      const blink::WebURL& url);
-  virtual bool allowRunningInsecureContent(
+      const blink::WebURL& url) override;
+  bool allowRunningInsecureContent(
       bool enabled_per_settings,
       const blink::WebSecurityOrigin& origin,
-      const blink::WebURL& url);
+      const blink::WebURL& url) override;
 
   DISALLOW_COPY_AND_ASSIGN(AwContentSettingsClient);
 };
diff --git a/build/common.gypi b/build/common.gypi
index 544f964..6b2cb0a 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -2227,7 +2227,8 @@
               'clang_dynlib_flags%': '',
             }],
           ],
-          'clang_plugin_args%': '-Xclang -plugin-arg-find-bad-constructs -Xclang check-templates ',
+          'clang_plugin_args%': '-Xclang -plugin-arg-find-bad-constructs -Xclang check-templates '
+          '-Xclang -plugin-arg-find-bad-constructs -Xclang enforce-overriding-blink ',
         },
         # If you change these, also change build/config/clang/BUILD.gn.
         'clang_chrome_plugins_flags%':
diff --git a/build/config/clang/BUILD.gn b/build/config/clang/BUILD.gn
index 02c5f2c..e560431 100644
--- a/build/config/clang/BUILD.gn
+++ b/build/config/clang/BUILD.gn
@@ -40,6 +40,10 @@ config("find_bad_constructs") {
       "-plugin-arg-find-bad-constructs",
       "-Xclang",
       "check-templates",
+      "-Xclang",
+      "-plugin-arg-find-bad-constructs",
+      "-Xclang",
+      "enforce-overriding-blink",
     ]
   }
 }
diff --git a/cc/blink/web_scroll_offset_animation_curve_impl.h b/cc/blink/web_scroll_offset_animation_curve_impl.h
index 32c6fb9..3a21853 100644
--- a/cc/blink/web_scroll_offset_animation_curve_impl.h
+++ b/cc/blink/web_scroll_offset_animation_curve_impl.h
@@ -33,8 +33,8 @@ class WebScrollOffsetAnimationCurveImpl
   blink::WebFloatPoint getValue(double time) const override;
   double duration() const override;
 
-  virtual blink::WebFloatPoint targetValue() const;
-  virtual void updateTarget(double time, blink::WebFloatPoint new_target);
+  blink::WebFloatPoint targetValue() const override;
+  void updateTarget(double time, blink::WebFloatPoint new_target) override;
 
   scoped_ptr<cc::AnimationCurve> CloneToAnimationCurve() const;
 
diff --git a/components/test_runner/mock_web_theme_engine.h b/components/test_runner/mock_web_theme_engine.h
index 362ed02..fc6d0ac 100644
--- a/components/test_runner/mock_web_theme_engine.h
+++ b/components/test_runner/mock_web_theme_engine.h
@@ -15,12 +15,12 @@ class MockWebThemeEngine : public blink::WebThemeEngine {
 
 #if !defined(OS_MACOSX)
   // blink::WebThemeEngine:
-  virtual blink::WebSize getSize(blink::WebThemeEngine::Part);
-  virtual void paint(blink::WebCanvas*,
-                     blink::WebThemeEngine::Part,
-                     blink::WebThemeEngine::State,
-                     const blink::WebRect&,
-                     const blink::WebThemeEngine::ExtraParams*);
+  blink::WebSize getSize(blink::WebThemeEngine::Part) override;
+  void paint(blink::WebCanvas*,
+             blink::WebThemeEngine::Part,
+             blink::WebThemeEngine::State,
+             const blink::WebRect&,
+             const blink::WebThemeEngine::ExtraParams*) override;
 #endif  // !defined(OS_MACOSX)
 };
 
diff --git a/content/browser/android/in_process/context_provider_in_process.cc b/content/browser/android/in_process/context_provider_in_process.cc
index 71f8010..cd9bd7d 100644
--- a/content/browser/android/in_process/context_provider_in_process.cc
+++ b/content/browser/android/in_process/context_provider_in_process.cc
@@ -25,11 +25,11 @@ class ContextProviderInProcess::LostContextCallbackProxy
     provider_->WebContext3DImpl()->setContextLostCallback(this);
   }
 
-  virtual ~LostContextCallbackProxy() {
+  ~LostContextCallbackProxy() override {
     provider_->WebContext3DImpl()->setContextLostCallback(NULL);
   }
 
-  virtual void onContextLost() {
+  void onContextLost() override {
     provider_->OnLostContext();
   }
 
diff --git a/content/child/blink_platform_impl.h b/content/child/blink_platform_impl.h
index b6850f2..c77dd9a 100644
--- a/content/child/blink_platform_impl.h
+++ b/content/child/blink_platform_impl.h
@@ -119,7 +119,7 @@ class CONTENT_EXPORT BlinkPlatformImpl
       const char* category_name) override;
   TraceEventAPIAtomicWord* getTraceSamplingState(
       const unsigned thread_bucket) override;
-  virtual TraceEventHandle addTraceEvent(
+  TraceEventHandle addTraceEvent(
       char phase,
       const unsigned char* category_group_enabled,
       const char* name,
@@ -131,7 +131,7 @@ class CONTENT_EXPORT BlinkPlatformImpl
       const unsigned char* arg_types,
       const unsigned long long* arg_values,
       blink::WebConvertableToTraceFormat* convertable_values,
-      unsigned int flags);
+      unsigned int flags) override;
   virtual TraceEventHandle addTraceEvent(
       char phase,
       const unsigned char* category_group_enabled,
diff --git a/content/child/service_worker/service_worker_dispatcher_unittest.cc b/content/child/service_worker/service_worker_dispatcher_unittest.cc
index 5df0501..93d9465 100644
--- a/content/child/service_worker/service_worker_dispatcher_unittest.cc
+++ b/content/child/service_worker/service_worker_dispatcher_unittest.cc
@@ -116,13 +116,13 @@ class MockWebServiceWorkerProviderClientImpl
     dispatcher_->AddProviderClient(provider_id, this);
   }
 
-  ~MockWebServiceWorkerProviderClientImpl() {
+  ~MockWebServiceWorkerProviderClientImpl() override {
     dispatcher_->RemoveProviderClient(provider_id_);
   }
 
   void setController(
       blink::WebPassOwnPtr<blink::WebServiceWorker::Handle> handle,
-      bool shouldNotifyControllerChange) {
+      bool shouldNotifyControllerChange) override {
     // WebPassOwnPtr cannot be owned in Chromium, so drop the handle here.
     // The destruction releases ServiceWorkerHandleReference.
     is_set_controlled_called_ = true;
diff --git a/content/child/webthemeengine_impl_android.h b/content/child/webthemeengine_impl_android.h
index e641a60..3483ab5 100644
--- a/content/child/webthemeengine_impl_android.h
+++ b/content/child/webthemeengine_impl_android.h
@@ -12,13 +12,12 @@ namespace content {
 class WebThemeEngineImpl : public blink::WebThemeEngine {
  public:
   // WebThemeEngine methods:
-  virtual blink::WebSize getSize(blink::WebThemeEngine::Part);
-  virtual void paint(
-      blink::WebCanvas* canvas,
-      blink::WebThemeEngine::Part part,
-      blink::WebThemeEngine::State state,
-      const blink::WebRect& rect,
-      const blink::WebThemeEngine::ExtraParams* extra_params);
+  blink::WebSize getSize(blink::WebThemeEngine::Part) override;
+  void paint(blink::WebCanvas* canvas,
+             blink::WebThemeEngine::Part part,
+             blink::WebThemeEngine::State state,
+             const blink::WebRect& rect,
+             const blink::WebThemeEngine::ExtraParams* extra_params) override;
 };
 
 }  // namespace content
diff --git a/content/child/webthemeengine_impl_default.h b/content/child/webthemeengine_impl_default.h
index a05313a..df25238 100644
--- a/content/child/webthemeengine_impl_default.h
+++ b/content/child/webthemeengine_impl_default.h
@@ -12,13 +12,12 @@ namespace content {
 class WebThemeEngineImpl : public blink::WebThemeEngine {
  public:
   // WebThemeEngine methods:
-  virtual blink::WebSize getSize(blink::WebThemeEngine::Part);
-  virtual void paint(
-      blink::WebCanvas* canvas,
-      blink::WebThemeEngine::Part part,
-      blink::WebThemeEngine::State state,
-      const blink::WebRect& rect,
-      const blink::WebThemeEngine::ExtraParams* extra_params);
+  blink::WebSize getSize(blink::WebThemeEngine::Part) override;
+  void paint(blink::WebCanvas* canvas,
+             blink::WebThemeEngine::Part part,
+             blink::WebThemeEngine::State state,
+             const blink::WebRect& rect,
+             const blink::WebThemeEngine::ExtraParams* extra_params) override;
   virtual void paintStateTransition(blink::WebCanvas* canvas,
                                     blink::WebThemeEngine::Part part,
                                     blink::WebThemeEngine::State startState,
diff --git a/content/ppapi_plugin/ppapi_blink_platform_impl.cc b/content/ppapi_plugin/ppapi_blink_platform_impl.cc
index ddfdc78..de977b2 100644
--- a/content/ppapi_plugin/ppapi_blink_platform_impl.cc
+++ b/content/ppapi_plugin/ppapi_blink_platform_impl.cc
@@ -45,9 +45,10 @@ class PpapiBlinkPlatformImpl::SandboxSupport : public WebSandboxSupport {
   bool loadFont(NSFont* srcFont, CGFontRef* out, uint32_t* fontID) override;
 #elif defined(OS_POSIX)
   SandboxSupport();
-  void getFallbackFontForCharacter(WebUChar32 character,
-                                   const char* preferred_locale,
-                                   blink::WebFallbackFont* fallbackFont);
+  void getFallbackFontForCharacter(
+      WebUChar32 character,
+      const char* preferred_locale,
+      blink::WebFallbackFont* fallbackFont) override;
   void getRenderStyleForStrike(const char* family,
                                int sizeAndStyle,
                                blink::WebFontRenderStyle* out) override;
diff --git a/content/renderer/media/android/media_info_loader.h b/content/renderer/media/android/media_info_loader.h
index b421fb3..067e580 100644
--- a/content/renderer/media/android/media_info_loader.h
+++ b/content/renderer/media/android/media_info_loader.h
@@ -59,7 +59,7 @@ class CONTENT_EXPORT MediaInfoLoader : private blink::WebURLLoaderClient {
       const GURL& url,
       blink::WebMediaPlayer::CORSMode cors_mode,
       const ReadyCB& ready_cb);
-  virtual ~MediaInfoLoader();
+  ~MediaInfoLoader() override;
 
   // Start loading media info.
   void Start(blink::WebFrame* frame);
@@ -80,32 +80,25 @@ class CONTENT_EXPORT MediaInfoLoader : private blink::WebURLLoaderClient {
       blink::WebURLLoader* loader,
       blink::WebURLRequest& newRequest,
       const blink::WebURLResponse& redirectResponse);
-  virtual void didSendData(
-      blink::WebURLLoader* loader,
-      unsigned long long bytesSent,
-      unsigned long long totalBytesToBeSent);
-  virtual void didReceiveResponse(
-      blink::WebURLLoader* loader,
-      const blink::WebURLResponse& response);
-  virtual void didDownloadData(
-      blink::WebURLLoader* loader,
-      int data_length,
-      int encodedDataLength);
-  virtual void didReceiveData(
-      blink::WebURLLoader* loader,
-      const char* data,
-      int data_length,
-      int encoded_data_length);
-  virtual void didReceiveCachedMetadata(
-      blink::WebURLLoader* loader,
-      const char* data, int dataLength);
-  virtual void didFinishLoading(
-      blink::WebURLLoader* loader,
-      double finishTime,
-      int64_t total_encoded_data_length);
-  virtual void didFail(
-      blink::WebURLLoader* loader,
-      const blink::WebURLError&);
+  void didSendData(blink::WebURLLoader* loader,
+                   unsigned long long bytesSent,
+                   unsigned long long totalBytesToBeSent) override;
+  void didReceiveResponse(blink::WebURLLoader* loader,
+                          const blink::WebURLResponse& response) override;
+  void didDownloadData(blink::WebURLLoader* loader,
+                       int data_length,
+                       int encodedDataLength) override;
+  void didReceiveData(blink::WebURLLoader* loader,
+                      const char* data,
+                      int data_length,
+                      int encoded_data_length) override;
+  void didReceiveCachedMetadata(blink::WebURLLoader* loader,
+                                const char* data,
+                                int dataLength) override;
+  void didFinishLoading(blink::WebURLLoader* loader,
+                        double finishTime,
+                        int64_t total_encoded_data_length) override;
+  void didFail(blink::WebURLLoader* loader, const blink::WebURLError&) override;
 
   void DidBecomeReady(Status status);
 
diff --git a/content/renderer/media/android/webmediaplayer_android.h b/content/renderer/media/android/webmediaplayer_android.h
index d9b7fe8..5b41f2c 100644
--- a/content/renderer/media/android/webmediaplayer_android.h
+++ b/content/renderer/media/android/webmediaplayer_android.h
@@ -97,44 +97,44 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
       scoped_refptr<StreamTextureFactory> factory,
       int frame_id,
       const media::WebMediaPlayerParams& params);
-  virtual ~WebMediaPlayerAndroid();
+  ~WebMediaPlayerAndroid() override;
 
   // blink::WebMediaPlayer implementation.
-  virtual bool supportsOverlayFullscreenVideo();
-  virtual void enterFullscreen();
+  bool supportsOverlayFullscreenVideo() override;
+  void enterFullscreen() override;
 
   // Resource loading.
-  virtual void load(LoadType load_type,
-                    const blink::WebURL& url,
-                    CORSMode cors_mode);
+  void load(LoadType load_type,
+            const blink::WebURL& url,
+            CORSMode cors_mode) override;
 
   // Playback controls.
-  virtual void play();
-  virtual void pause();
-  virtual void seek(double seconds);
-  virtual bool supportsSave() const;
-  virtual void setRate(double rate);
-  virtual void setVolume(double volume);
-  virtual void setSinkId(const blink::WebString& sink_id,
-                         const blink::WebSecurityOrigin& security_origin,
-                         blink::WebSetSinkIdCallbacks* web_callback);
-  virtual void requestRemotePlayback();
-  virtual void requestRemotePlaybackControl();
-  virtual blink::WebTimeRanges buffered() const;
-  virtual blink::WebTimeRanges seekable() const;
+  void play() override;
+  void pause() override;
+  void seek(double seconds) override;
+  bool supportsSave() const override;
+  void setRate(double rate) override;
+  void setVolume(double volume) override;
+  void setSinkId(const blink::WebString& sink_id,
+                 const blink::WebSecurityOrigin& security_origin,
+                 blink::WebSetSinkIdCallbacks* web_callback) override;
+  void requestRemotePlayback() override;
+  void requestRemotePlaybackControl() override;
+  blink::WebTimeRanges buffered() const override;
+  blink::WebTimeRanges seekable() const override;
 
   // Poster image, as defined in the <video> element.
-  virtual void setPoster(const blink::WebURL& poster) override;
+  void setPoster(const blink::WebURL& poster) override;
 
   // Methods for painting.
   // FIXME: This path "only works" on Android. It is a workaround for the
   // issue that Skia could not handle Android's GL_TEXTURE_EXTERNAL_OES texture
   // internally. It should be removed and replaced by the normal paint path.
   // https://code.google.com/p/skia/issues/detail?id=1189
-  virtual void paint(blink::WebCanvas* canvas,
-                     const blink::WebRect& rect,
-                     unsigned char alpha,
-                     SkXfermode::Mode mode);
+  void paint(blink::WebCanvas* canvas,
+             const blink::WebRect& rect,
+             unsigned char alpha,
+             SkXfermode::Mode mode) override;
 
   bool copyVideoTextureToPlatformTexture(
       blink::WebGraphicsContext3D* web_graphics_context,
@@ -145,37 +145,37 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
       bool flip_y) override;
 
   // True if the loaded media has a playable video/audio track.
-  virtual bool hasVideo() const;
-  virtual bool hasAudio() const;
+  bool hasVideo() const override;
+  bool hasAudio() const override;
 
-  virtual bool isRemote() const;
+  bool isRemote() const override;
 
   // Dimensions of the video.
-  virtual blink::WebSize naturalSize() const;
+  blink::WebSize naturalSize() const override;
 
   // Getters of playback state.
-  virtual bool paused() const;
-  virtual bool seeking() const;
-  virtual double duration() const;
+  bool paused() const override;
+  bool seeking() const override;
+  double duration() const override;
   virtual double timelineOffset() const;
-  virtual double currentTime() const;
+  double currentTime() const override;
 
-  virtual bool didLoadingProgress();
+  bool didLoadingProgress() override;
 
   // Internal states of loading and network.
-  virtual blink::WebMediaPlayer::NetworkState networkState() const;
-  virtual blink::WebMediaPlayer::ReadyState readyState() const;
+  blink::WebMediaPlayer::NetworkState networkState() const override;
+  blink::WebMediaPlayer::ReadyState readyState() const override;
 
-  virtual bool hasSingleSecurityOrigin() const;
-  virtual bool didPassCORSAccessCheck() const;
+  bool hasSingleSecurityOrigin() const override;
+  bool didPassCORSAccessCheck() const override;
 
-  virtual double mediaTimeForTimeValue(double timeValue) const;
+  double mediaTimeForTimeValue(double timeValue) const override;
 
   // Provide statistics.
-  virtual unsigned decodedFrameCount() const;
-  virtual unsigned droppedFrameCount() const;
-  virtual unsigned audioDecodedByteCount() const;
-  virtual unsigned videoDecodedByteCount() const;
+  unsigned decodedFrameCount() const override;
+  unsigned droppedFrameCount() const override;
+  unsigned audioDecodedByteCount() const override;
+  unsigned videoDecodedByteCount() const override;
 
   // cc::VideoFrameProvider implementation. These methods are running on the
   // compositor thread.
@@ -233,24 +233,22 @@ class WebMediaPlayerAndroid : public blink::WebMediaPlayer,
   const gfx::RectF GetBoundaryRectangle();
 #endif  // defined(VIDEO_HOLE)
 
-  virtual MediaKeyException generateKeyRequest(
+  MediaKeyException generateKeyRequest(const blink::WebString& key_system,
+                                       const unsigned char* init_data,
+                                       unsigned init_data_length) override;
+  MediaKeyException addKey(const blink::WebString& key_system,
+                           const unsigned char* key,
+                           unsigned key_length,
+                           const unsigned char* init_data,
+                           unsigned init_data_length,
+                           const blink::WebString& session_id) override;
+  MediaKeyException cancelKeyRequest(
       const blink::WebString& key_system,
-      const unsigned char* init_data,
-      unsigned init_data_length);
-  virtual MediaKeyException addKey(
-      const blink::WebString& key_system,
-      const unsigned char* key,
-      unsigned key_length,
-      const unsigned char* init_data,
-      unsigned init_data_length,
-      const blink::WebString& session_id);
-  virtual MediaKeyException cancelKeyRequest(
-      const blink::WebString& key_system,
-      const blink::WebString& session_id);
+      const blink::WebString& session_id) override;
 
-  virtual void setContentDecryptionModule(
+  void setContentDecryptionModule(
       blink::WebContentDecryptionModule* cdm,
-      blink::WebContentDecryptionModuleResult result);
+      blink::WebContentDecryptionModuleResult result) override;
 
   void OnKeyAdded(const std::string& session_id);
   void OnKeyError(const std::string& session_id,
diff --git a/content/renderer/media/android/webmediasession_android.h b/content/renderer/media/android/webmediasession_android.h
index 8e31d1d3..576079f 100644
--- a/content/renderer/media/android/webmediasession_android.h
+++ b/content/renderer/media/android/webmediasession_android.h
@@ -16,7 +16,7 @@ class RendererMediaSessionManager;
 class CONTENT_EXPORT WebMediaSessionAndroid : public blink::WebMediaSession {
  public:
   WebMediaSessionAndroid(RendererMediaSessionManager* session_manager);
-  virtual ~WebMediaSessionAndroid() override;
+  ~WebMediaSessionAndroid() override;
 
   void activate(blink::WebMediaSessionActivateCallback*) override;
   void deactivate(blink::WebMediaSessionDeactivateCallback*) override;
diff --git a/content/renderer/media/canvas_capture_handler.h b/content/renderer/media/canvas_capture_handler.h
index a7d54d2..05e5bdc 100644
--- a/content/renderer/media/canvas_capture_handler.h
+++ b/content/renderer/media/canvas_capture_handler.h
@@ -41,7 +41,7 @@ class CONTENT_EXPORT CanvasCaptureHandler final
   blink::WebSize GetSourceSize() const { return size_; }
 
  private:
-  virtual ~CanvasCaptureHandler();
+  ~CanvasCaptureHandler() override;
 
   void CreateNewFrame(const blink::WebSkImage& image);
 
diff --git a/content/renderer/render_frame_impl.h b/content/renderer/render_frame_impl.h
index c357ff8..baed47f 100644
--- a/content/renderer/render_frame_impl.h
+++ b/content/renderer/render_frame_impl.h
@@ -432,7 +432,7 @@ class CONTENT_EXPORT RenderFrameImpl
                      const blink::WebString& name) override;
   void didChangeSandboxFlags(blink::WebFrame* child_frame,
                              blink::WebSandboxFlags flags) override;
-  virtual void didChangeFrameOwnerProperties(
+  void didChangeFrameOwnerProperties(
       blink::WebFrame* child_frame,
       const blink::WebFrameOwnerProperties& frame_owner_properties) override;
   void didMatchCSS(
diff --git a/content/renderer/vr/vr_dispatcher.h b/content/renderer/vr/vr_dispatcher.h
index 7e5d56b..1dc79f4 100644
--- a/content/renderer/vr/vr_dispatcher.h
+++ b/content/renderer/vr/vr_dispatcher.h
@@ -20,7 +20,7 @@ class ServiceRegistry;
 class VRDispatcher : NON_EXPORTED_BASE(public blink::WebVRClient) {
  public:
   explicit VRDispatcher(ServiceRegistry* service_registry);
-  ~VRDispatcher();
+  ~VRDispatcher() override;
 
   // blink::WebVRClient implementation.
   void getDevices(blink::WebVRGetDevicesCallback* callback) override;
diff --git a/content/renderer/wake_lock/wake_lock_dispatcher.h b/content/renderer/wake_lock/wake_lock_dispatcher.h
index e36a3e0..70ce86a 100644
--- a/content/renderer/wake_lock/wake_lock_dispatcher.h
+++ b/content/renderer/wake_lock/wake_lock_dispatcher.h
@@ -21,7 +21,7 @@ class WakeLockDispatcher : public RenderFrameObserver,
 
  private:
   // WebWakeLockClient implementation.
-  virtual void requestKeepScreenAwake(bool keepScreenAwake);
+  void requestKeepScreenAwake(bool keepScreenAwake) override;
 
   WakeLockServicePtr wake_lock_service_;
 };
diff --git a/content/renderer/webscrollbarbehavior_impl_gtkoraura.h b/content/renderer/webscrollbarbehavior_impl_gtkoraura.h
index 30ccb23..3b0eb61 100644
--- a/content/renderer/webscrollbarbehavior_impl_gtkoraura.h
+++ b/content/renderer/webscrollbarbehavior_impl_gtkoraura.h
@@ -11,13 +11,12 @@ namespace content {
 
 class WebScrollbarBehaviorImpl : public blink::WebScrollbarBehavior {
  public:
-  virtual bool shouldCenterOnThumb(
-      blink::WebScrollbarBehavior::Button mouseButton,
-      bool shiftKeyPressed,
-      bool altKeyPressed);
-  virtual bool shouldSnapBackToDragOrigin(const blink::WebPoint& eventPoint,
-                                          const blink::WebRect& scrollbarRect,
-                                          bool isHorizontal);
+  bool shouldCenterOnThumb(blink::WebScrollbarBehavior::Button mouseButton,
+                           bool shiftKeyPressed,
+                           bool altKeyPressed) override;
+  bool shouldSnapBackToDragOrigin(const blink::WebPoint& eventPoint,
+                                  const blink::WebRect& scrollbarRect,
+                                  bool isHorizontal) override;
 };
 
 }  // namespace content
diff --git a/media/blink/multibuffer_data_source_unittest.cc b/media/blink/multibuffer_data_source_unittest.cc
index 661840d..3890af9 100644
--- a/media/blink/multibuffer_data_source_unittest.cc
+++ b/media/blink/multibuffer_data_source_unittest.cc
@@ -47,7 +47,7 @@ class TestMultiBufferDataProvider : public ResourceMultiBufferDataProvider {
       : ResourceMultiBufferDataProvider(url_data, pos), loading_(false) {
     CHECK(test_data_providers.insert(this).second);
   }
-  ~TestMultiBufferDataProvider() {
+  ~TestMultiBufferDataProvider() override {
     CHECK_EQ(static_cast<size_t>(1), test_data_providers.erase(this));
   }
   void Start() override {