[video_player_platform_interface] Improve seek performance on Android

[sailendrabathi]

Adds backBufferDurationMs to video_player_platform_interface

This PR has only the platform interface package changes from the main PR: #11810.

Following PR split as per Changing federated plugins

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[gemini-code-assist]

Code Review

This pull request introduces backBufferDurationMs to VideoPlayerOptions to configure ExoPlayer's back buffer duration on Android, and adds videoPlayerOptions to VideoCreationOptions. Feedback suggests updating the assertion to allow a value of 0 (enabling developers to disable back buffering) and correcting the markdown spacing in the documentation comment for proper bold rendering.

[mboetger]

Holding on for ecosystem review

[sailendrabathi]

@mboetger, I updated the PR after approval from ecosystem reviewer.

Comment link for reference: #11810 (review)

[stuartmorgan-g]

We don't make assertions about what platforms implement something in platform interface packgaes, because this package doesn't control that. What if a third-party implementation for another platform supports it, for instance? Or it's added to iOS later, without any change to this package?

We also don't describe behavior in terms of underlying SDK details unless there's no other way to. This comment should describe what the back buffer is, conceptually, without reference to ExoPlayer.

[stuartmorgan-g]

Same here. You can say "Ignored on platforms that do not support controlling the back buffer.", which is both generic to other implementations, and future-proof.

[tarrinneal]

I was going to say this, but I figured once the interface is reworked to use the new standard of supportsX I would remove it myself.

[tarrinneal]

but Stuart is right, that is protocol

[stuartmorgan-g]

It's not just protocol; this class is directly re-exported from the app-facing package currently, so these will be client-facing docs as soon as they land.

[stuartmorgan-g]

Same here; don't reference ExoPlayer or Android.

[stuartmorgan-g]

Composing the two different options classes seems potentially confusing, but it doesn't look like the API surface ever clearly distinguished these conceptually. Since VideoCreationOptions isn't exposed to app-level clients it's probably not a big deal.

@tarrinneal As part of revisiting the video_player API surface later, it would be good to better distinguish what classes are for what steps of the process (e.g., global vs player-level options, which may have been the original intent here?), and we should also fix the fact that some of these classes are being directly re-exported from the app-facing package, which we should stop doing.