The following assertions are observed in the log: I/Gecko ( 105): ###!!! ASSERTION: Main thread only: 'NS_IsMainThread()', file /home/mikeh/dev/mozilla/btg012/gecko/content/media/MediaStreamGraph.cpp, line 2039 I/Gecko ( 105): ###!!! ASSERTION: Using observer service off the main thread!: 'Error', file /home/mikeh/dev/mozilla/btg012/gecko/xpcom/ds/nsObserverService.cpp, line 95 I/Gecko ( 105): ###!!! ASSERTION: main thread only: 'NS_IsMainThread()', file /home/mikeh/dev/mozilla/btg012/gecko/content/media/MediaStreamGraph.cpp, line 1638 I/Gecko ( 105): ###!!! ASSERTION: main thread only: 'NS_IsMainThread()', file /home/mikeh/dev/mozilla/btg012/gecko/content/media/MediaStreamGraph.cpp, line 1609 I/Gecko ( 105): ###!!! ASSERTION: Should be on main thread.: 'NS_IsMainThread()', file /home/mikeh/dev/mozilla/btg012/gecko/widget/xpwidgets/nsBaseAppShell.cpp, line 367 I/Gecko ( 105): ###!!! ASSERTION: Wrong thread!: 'NS_IsMainThread()', file /home/mikeh/dev/mozilla/btg012/gecko/widget/xpwidgets/nsBaseAppShell.cpp, line 320 I/Gecko ( 105): ###!!! ASSERTION: main thread only: 'NS_IsMainThread()', file /home/mikeh/dev/mozilla/btg012/gecko/content/media/MediaStreamGraph.cpp, line 1638 I/Gecko ( 105): ###!!! ASSERTION: main thread only: 'NS_IsMainThread()', file /home/mikeh/dev/mozilla/btg012/gecko/content/media/MediaStreamGraph.cpp, line 1609

MediaStream configuration is handled on the main thread; consumption change events are handled separately on the camera thread.

Comment on attachment 647759 [details] [diff] [review] MediaStreams on the main thread Review of attachment 647759 [details] [diff] [review]: ----------------------------------------------------------------- Sorry, I should have caught this during review. ::: dom/camera/CameraPreview.cpp @@ +62,5 @@ > nsCOMPtr<CameraPreview> mPreview; > }; > > +// Control the preview stream source. > +class CameraPreviewControlTask : public nsRunnable Can you use NS_NewRunnableMethod instead of this class?

:roc: no worries--that was a lot of code to go over all at once.