Refine Demuxer GC for low resolution videos

[jasonzhangxx]

The chunk demuxer garbage collection algorithm didn't account
bookkeeping data, which uses a significant amount of memory when
playing low resolution videos. For example, the reported memory usage of
ChunkDemuxerTest.WebMFile_AudioOnly test was 18624 bytes. After
including memory usage of 166 StreamParserBuffer instances, the new
memory usage increases to 69088 bytes.

This change is backported from m126+.

Fixed: b/372965149
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5353702
(cherry picked from commit 41153e57b9e6a7ef8dd2231dfc8cab201a956913)

[jasonzhangxx]

Note that the code had some conflicts in media/base/decoder_buffer.cc, media/base/decoder_buffer.h, media/filters/source_buffer_state.cc and has been resolved.

[borongc]

Do we know which Chromium milestone contains this upstream PR, and maybe make a note here, so when we rebase to later milestones, we will know if this is needed?

[borongc]

It's available on m126+.

Maybe consider to include this cherry pick PR is available on m126+ in the commit message.

[jasonzhangxx]

As it's cherry-picked from chromium repo, I'm not sure what git will do when rebasing to later chromium version which includes the original commit. The commit message is the same as in the original chromium change. @andrewsavage1, @dahlstrom-g, what do you think about Borong's comment?

[andrewsavage1]

I'd defer to @dahlstrom-g about if we care about changing the original commit message, but it won't interfere with git history when we rebase if we do.

[kaidokert]

As it's cherry-picked from chromium repo, I'm not sure what git will do when rebasing to later chromium version which includes the original commit.

Because we work off of squashed copy of upstream code, don't expect git to provide automatic resolution. We pretty much need to manually annotate and keep track of things we cherry-picked and can discard later.

Adding an extra line to the commit message doesn't seem like a bad idea, but we don't really have a convention captured anywhere for this yet.

[jasonzhangxx]

Ok, added a line to explicitly mention it's from m126+.

[andrewsavage1]

Bypassing lint check, as it's incorrectly checking files unrelated to this change