virtual void DrainComplete() override
 {
   if (mManager->mActiveCallback) {
     AssertHaveActiveProxy();
     mManager->DrainComplete();
   }
 }
 virtual void InputExhausted() override
 {
   if (mManager->mActiveCallback) {
     AssertHaveActiveProxy();
     mManager->mActiveCallback->InputExhausted();
   }
 }
 virtual void Output(MediaData* aData) override
 {
   if (mManager->mActiveCallback) {
     AssertHaveActiveProxy();
     mManager->mActiveCallback->Output(aData);
   }
 }
 virtual void Error() override
 {
   if (mManager->mActiveCallback) {
     AssertHaveActiveProxy();
     mManager->mActiveCallback->Error();
   }
 }
 virtual void ReleaseMediaResources() override
 {
   if (mManager->mActiveCallback) {
     AssertHaveActiveProxy();
     mManager->mActiveCallback->ReleaseMediaResources();
   }
 }