PSA: Use accessors for codec specific infomation in webrtc::VideoCodec

[Harald Alvestrand]

If you have code that includes webrtc/common_types.h and looks like this:

webrtc::VideoCodec foo;

foo.codecSpecificInfo.VP8.somefield = somevalue

you need to change it to use an accessor.

For write access, there's an accessor that returns a pointer:

foo.VP8()->somefield = somevalue

For read access, the accessor returns a const reference:

value = foo.VP8().somefield

If you access the wrong type of codec-specific info, there is a DCHECK that will generate an error (in debug mode), so there's a whole class of errors that shouldn't be possible to do any more.

I expect to land the CL that makes the old field private in about 2 weeks from now.

Harald Alvestrand

[Harald Alvestrand]

This change has now landed.