Bug 583205 - Crash at the time of download completion. r=karlt,a=blocker

widget/src/gtk2/nsImageToPixbuf.cpp

@@ -69,10 +69,22 @@ GdkPixbuf*
 nsImageToPixbuf::ImageToPixbuf(imgIContainer* aImage)
 {
     nsRefPtr<gfxImageSurface> frame;
-    aImage->CopyFrame(imgIContainer::FRAME_CURRENT,
+    nsresult rv = aImage->CopyFrame(imgIContainer::FRAME_CURRENT,
                                     imgIContainer::FLAG_SYNC_DECODE,
                                     getter_AddRefs(frame));
 
+    // If the last call failed, it was probably because our call stack originates
+    // in an imgIDecoderObserver event, meaning that we're not allowed request
+    // a sync decode. Presumably the originating event is something sensible like
+    // OnStopFrame(), so we can just retry the call without a sync decode.
+    if (NS_FAILED(rv))
+        aImage->CopyFrame(imgIContainer::FRAME_CURRENT,
+                          imgIContainer::FLAG_NONE,
+                          getter_AddRefs(frame));
+
+    if (!frame)
+      return nsnull;
+
     return ImgSurfaceToPixbuf(frame, frame->Width(), frame->Height());
 }