if (mCacheEntry) mCacheEntry->SetDataSize(0);  return NS_OK;
NS_IMETHODIMP imgRequest::OnStartDecode(imgIRequest *request){  LOG_SCOPE(gImgLog, "imgRequest::OnStartDecode");  mState |= onStartDecode;  PRInt32 count = mObservers.Count();  for (PRInt32 i = 0; i < count; i++) {    imgRequestProxy *proxy = NS_STATIC_CAST(imgRequestProxy*, mObservers[i]);    if (proxy) proxy->OnStartDecode();    // If this assertion fires, it means that imgRequest notifications could    // be dropped!    NS_ASSERTION(count == mObservers.Count(),                  "The observer list changed while being iterated over!");  }  /* In the case of streaming jpegs, it is possible to get multiple OnStartDecodes which     indicates the beginning of a new decode.     The cache entry's size therefore needs to be reset to 0 here.  If we do not do this,     the code in imgRequest::OnStopFrame will continue to increase the data size cumulatively.   */  if (mCacheEntry)    mCacheEntry->SetDataSize(0);  return NS_OK;}