Update modules classes to use OVERRIDE / FINAL when needed

Source/modules/mediasource/SourceBuffer.h

Index: Source/modules/mediasource/SourceBuffer.h
diff --git a/Source/modules/mediasource/SourceBuffer.h b/Source/modules/mediasource/SourceBuffer.h
index c7ada7c48d875d20f0edd3608e95857cf2660644..884aa57179fbc1e1b44c0d5ce0f2ea43da652e83 100644
--- a/Source/modules/mediasource/SourceBuffer.h
+++ b/Source/modules/mediasource/SourceBuffer.h
@@ -57,7 +57,7 @@ class MediaSource;
 class Stream;
 class TimeRanges;
 
-class SourceBuffer : public RefCounted<SourceBuffer>, public ActiveDOMObject, public EventTargetWithInlineData, public ScriptWrappable, public FileReaderLoaderClient {
+class SourceBuffer FINAL : public RefCounted<SourceBuffer>, public ActiveDOMObject, public EventTargetWithInlineData, public ScriptWrappable, public FileReaderLoaderClient {
     REFCOUNTED_EVENT_TARGET(SourceBuffer);
 public:
     static PassRefPtr<SourceBuffer> create(PassOwnPtr<blink::WebSourceBuffer>, MediaSource*, GenericEventQueue*);