Add missing traces for Supplement<> classes

third_party/WebKit/Source/modules/audio_output_devices/AudioOutputDeviceClient.h

Index: third_party/WebKit/Source/modules/audio_output_devices/AudioOutputDeviceClient.h
diff --git a/third_party/WebKit/Source/modules/audio_output_devices/AudioOutputDeviceClient.h b/third_party/WebKit/Source/modules/audio_output_devices/AudioOutputDeviceClient.h
index 7d824bdbd77c471c8b374cca91eaa16615f7ada6..363c4aec87c9005f4439639a8979398458c435e5 100644
--- a/third_party/WebKit/Source/modules/audio_output_devices/AudioOutputDeviceClient.h
+++ b/third_party/WebKit/Source/modules/audio_output_devices/AudioOutputDeviceClient.h
@@ -5,6 +5,7 @@
 #ifndef AudioOutputDeviceClient_h
 #define AudioOutputDeviceClient_h
 
+#include "core/frame/LocalFrame.h"
 #include "modules/ModulesExport.h"
 #include "platform/Supplementable.h"
 #include "public/platform/WebSetSinkIdCallbacks.h"
@@ -13,17 +14,18 @@
 namespace blink {
 
 class ExecutionContext;
-class LocalFrame;
 class WebString;
 class ScriptState;
 
-class AudioOutputDeviceClient : public Supplement<LocalFrame> {
+class MODULES_EXPORT AudioOutputDeviceClient : public Supplement<LocalFrame> {
 public:
     virtual ~AudioOutputDeviceClient() {}
 
     // Checks that a given sink exists and has permissions to be used from the origin of the current frame.
     virtual void checkIfAudioSinkExistsAndIsAuthorized(ExecutionContext*, const WebString& sinkId, std::unique_ptr<WebSetSinkIdCallbacks>) = 0;
 
+    DECLARE_VIRTUAL_TRACE();
+
     // Supplement requirements.
     static AudioOutputDeviceClient* from(ExecutionContext*);
     static const char* supplementName();