Make MediaCodecVideoRenderer::shouldUsePlaceholderSurface protected.

[khouzam]

This enables a derived renderer to disable the placeholder surface.

Not having a placeholder surface allows to delay instantiating the codecs until we have a surface. This allows to have more players ready without having their decoders loaded.

This follows the mode that shouldUseDetachedSurface is protected and overridable by a derived class.

Since getSurfaceForCodec must call hasSurfaceForCodec, the check for the placeholder surface in getSurfaceForCodec should not trigger if we disable the placeholder surface as hasSurfaceForCodec would have returned false.

[microkatz]

@khouzam

Thanks for submitting your request! Just a curiosity, have you looked at MediaCodecVideoRenderer::shouldInitCodec for your use case? Its already overridable and utilized by MediaCodecRenderer to decide if the decoder should be initialized.

[khouzam]

@microkatz Thanks for the suggestion, I'll experiment with it, but while this can prevent the initialization of the codec, it will still create the PlaceholderSurface when a null surface gets set.

[khouzam]

@microkatz We've tried your suggestion. The results don't seem very encouraging. We see significant increases in ANRs, memory kills and native crashes. The additional resources used by the placeholder surface seems to really conflict with some of the fine tuning that we've done for our scenarios.

[tonihei]

@microkatz: @khouzam and I discussed this code path in person as well and concluded that the protected access makes sense because the method is also used from setOutput where there is no other way to prevent the usage of placeholder surfaces if the codec already exists and the surface is removed.

[microkatz]

I'm going to send this for internal review now. You may see some more commits being added as I make changes in response to review feedback. Please refrain from pushing any more substantive changes as it will complicate the internal review - thanks!