Cherry pick PR #9145: media: Optimize Mojo IPC via batched sample writes in StarboardRenderer

[cobalt-github-releaser-bot]

Refer to the original PR: #9145

Refactor StarboardRenderer to support batched sample writes. This improves the efficiency of Mojo IPC between the Renderer and player_worker by reducing the overhead of high-frequency individual packet transfers.

Batching allows the renderer to "burst" data through the IPC layer whenever the thread has control. This reduces the pipeline's sensitivity to Renderer thread contention, ensuring a more stable data flow and decreasing the risk of playback being impacted by transient thread starvation or hangs.

Issue: 375674101

[cobalt-github-releaser-bot]

Caution

There were merge conflicts while cherry picking! Check out cherry-pick-main-9145 and fix the conflicts before proceeding. Check the log at https://github.com/youtube/cobalt/actions/runs/22450794750 for details.

[github-actions]

🤖 Gemini Suggested Commit Message

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media: Optimize IPC with batched sample writes

Refactor StarboardRenderer to support writing multiple samples at once.
This improves Mojo IPC efficiency between the Renderer and player_worker
by reducing the overhead of high-frequency individual transfers.

Batching allows the renderer to "burst" data through the IPC layer
whenever the thread has control. This reduces the pipeline's
sensitivity to Renderer thread contention, ensuring a more stable data
flow and decreasing the risk of playback being impacted by transient
thread starvation or hangs.

Bug: 375674101

---

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