Web Audio: Oilpan: Trace AudioSummingJunction::m_renderingOutputs

Web Audio: Oilpan: Trace AudioSummingJunction::m_renderingOutputs

m_renderingOutpus is a vector of AudioNodeOutput raw pointers.  They are raw
pointers because the vector is allocated in the audio rendering thread, which
has no Oilpan support.  However, They can be last references to the AudioNodeOutput
objects, and Oilpan GC during audio rendering could collect the objects.  We
need to trace the contents of m_renderingOutputs.

This CL fixes crashes.  But unused AudioNodes in the graph are not
destructed automatically unless JavaScript code explicitly disconnect
them from the graph.

BUG=434136
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=186914

[tkent, 2014-12-10 06:36:43]

tkent@chromium.org changed reviewers:
+ haraken@chromium.org, rtoy@chromium.org

[tkent, 2014-12-10 06:36:43]

Please review this.

Unfortunately the reproduction in the bug didn't crash with content_shell.

[haraken, 2014-12-10 07:08:19]

Add a FIXME as a comment. LGTM.

[Raymond Toy, 2014-12-10 18:00:31]

lgtm.

I don't believe content_shell has any support for a real audiocontext.  You can
create them, but they're not really functional. You have to use an offline
context.

And when you say Javascript must explicitly disconnect them, do you mean
Javascript needs to do node.disconnect() as well as discard the node reference?

[tkent, 2014-12-11 02:34:02]

On 2014/12/10 18:00:31, Raymond Toy wrote:
> lgtm.
> 
> I don't believe content_shell has any support for a real audiocontext.  You
can
> create them, but they're not really functional. You have to use an offline
> context.

I see.  Thank you for the information.

> And when you say Javascript must explicitly disconnect them, do you mean
> Javascript needs to do node.disconnect() as well as discard the node
reference?

Exactly right.

[tkent, 2014-12-11 02:34:12]

On 2014/12/10 07:08:19, haraken wrote:
> Add a FIXME as a comment. LGTM.

Done.

[tkent, 2014-12-11 02:34:19]

The CQ bit was checked by tkent@chromium.org

[commit-bot: I haz the power, 2014-12-11 02:34:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/782603004/20001

[commit-bot: I haz the power, 2014-12-11 05:10:52]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=186914