Auto-Contribute entries sometimes contain 'on YouTube' text twice

[LaurenWags]

Description

Some Auto-Contribute table entries contain text text of 'on YouTube' twice.

Steps to Reproduce

1. Be sure Rewards are enabled.
2. Visit some youtube videos. --> Verify they are added to the table.
3. Visit a site with an embedded YouTube video. --> Verify it is added to the table.

Actual result:

View table, some videos have 'on YouTube' text twice:

Expected result:

Should not have this text twice

Reproduces how often:

easily

Brave version (chrome://version info)

Brave	0.55.13 Chromium: 70.0.3538.54 (Official Build) beta(64-bit)
Revision	4f8e578b6680574714e9ed3bb9f02922b4dde40d-refs/branch-heads/3538@{#937}
OS	Mac OS X

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? yes, reproduced on Beta
• Does it reproduce on browser-laptop? no

Website problems only:

• Does the issue resolve itself when disabling Brave Shields? n/a
• Is the issue reproducible on the latest version of Chrome? n/a

Additional Information

Found while testing #986

[NejcZdovc]

I think this was fixed with media panel. Let's retest when brave/brave-core#699 lands

[LaurenWags]

Verified passed with

Brave	0.56.7 Chromium: 70.0.3538.77 (Official Build) beta(64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Mac OS X

• Verified STR from description
  

Verification Passed on

Brave	0.56.8 Chromium: 70.0.3538.77 (Official Build) (64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Windows

Verification Passed on

Brave	0.56.8 Chromium: 70.0.3538.77 (Official Build) (64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Linux