Duckplayer: 33. Fix video auto-pause issues

[afterxleep]

Task/Issue URL: https://app.asana.com/0/1204099484721401/1209253933548270
Tech Design URL:
CC:

Description:
In some cases, when watching videos in DuckPlayer, videos pause after a few seconds when in Always Ask mode.

The issue involves a backgrounded tab. Although our JavaScript pauses the video every 10 ms, YouTube attempts to play an ad and succeeds. The ad plays briefly before our JavaScript pauses it, which is enough to hijack the audio session from the Duckplayer view, pausing the video.

This fix mutes the opener tab audio if "Open in new tab" is enabled. Thus, even if an ad plays briefly, it doesn't steal the audio session.

Steps to test this PR:

1. Burn all data
2. Go to Settings > DuckPlayer
3. Make sure its in “Ask Every time” mode and Open videos in new tab is selected.
4. Go to YouTube.com
5. Tap the “You” tab on the bottom right
6. Tap the settings gear icon in the top right
7. Tap General
8. Turn off the toggle for “Video previews”
9. Close Settings and go back to Youtube
10. Search for mkbhd
11. Tap second video (Samsung Galaxy Something)
12. Tap “Watch in Duck Player”
13. Video should play without interruptions. (It was originally pausing at around 0:06s)

Definition of Done (Internal Only):

• Does this PR satisfy our Definition of Done?

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Internal references:

Software Engineering Expectations
Technical Design Template