Add config change support to FFmpegVideoDecoder

Add config change support to FFmpegVideoDecoder


BUG=122913
TEST=None

[acolwell GONE FROM CHROMIUM, 2012-07-12 01:21:25]

PTAL
Relies on the following changes
https://chromiumcodereview.appspot.com/10669022/
https://chromiumcodereview.appspot.com/10696182/

[acolwell GONE FROM CHROMIUM, 2012-07-12 01:24:09]

I know I still need to add tests. Just wanted to get all the changes up here so
you could see how this all relates to 10669022

[Ami GONE FROM CHROMIUM, 2012-07-13 00:59:05]

I don't understand what the natural_size business is all about, and I think it's
strange that even though it's a pretty constant thing, we end up setting it and
looking it up on every single frame.  Maybe f2f convo would help.

https://chromiumcodereview.appspot.com/10704175/diff/1/media/base/video_frame.h
File media/base/video_frame.h (right):

https://chromiumcodereview.appspot.com/10704175/diff/1/media/base/video_frame...
media/base/video_frame.h:53: size_t natural_width,
You need serious commentary about how the "natural_" prefix modifies the meaning
of the parameter.

https://chromiumcodereview.appspot.com/10704175/diff/1/media/filters/ffmpeg_v...
File media/filters/ffmpeg_video_decoder.cc (right):

https://chromiumcodereview.appspot.com/10704175/diff/1/media/filters/ffmpeg_v...
media/filters/ffmpeg_video_decoder.cc:163: if (!AllocateFFmpegResources(config))
{
I wonder if it doesn't make sense to inline AFFMR() into HandleConfigChange and
call the latter from here (and make it tolerant to not having a "previous" set
of ffmpeg resources to release).

https://chromiumcodereview.appspot.com/10704175/diff/1/media/filters/ffmpeg_v...
media/filters/ffmpeg_video_decoder.cc:172: frame_rate_denominator_ =
config.frame_rate_denominator();
...in which case these can go away