Enable Media Router (cast) feature by default on Desktop

[ShivanKaul]

We had previously disabled Media Router by default on Desktop (but enabled by default on Android). The Media Router feature (toggleable in brave://settings/extensions) allows a user to cast a Brave tab to a device such as a smart TV. During privacy review, we'd caught that when the Media Router feature was on, outgoing SSDP packets used the Brave user agent instead of the Chrome one like we do on the Web. This was fixed in #18017.

At this point I don't think there's much benefit to keeping this important feature disabled by default. We should enable by default, and let privacy-conscious users turn it off.

1. New profiles should have Media Router toggle ON by default.
2. Existing profiles should not be changed, to avoid us overriding users' preferences.

[MadhaviSeelam]

Verification PASSED using

Brave | 1.67.86 Chromium: 125.0.6422.60 (Official Build) beta (64-bit)
-- | --
Revision | a1f8e8f462d422d4b924fa9c34246f68862b21ad
OS | Windows 11 Version 23H2 (Build 22631.3593)

New Install

Case 1: New profile => Media Cast is ON

1. Install 1.67.86
2. launched Brave
3. opened brave://settings/extensions

• Confirmed Media Router is enabled by default
• Confirmed Cast option in the Share menu is shown

example	example

Upgrade

Case 2: Existing profile has Media Cast OFF => nothing changes

1. installed 1.66.110
2. launched Brave
3. opened brave://settings/extensions
4. verified Media router is disabled by default
5. closed the browser and renamed the profile to brave-browser-beta
6. installed 1.67.86
7. launched Brave
8. opened brave://settings/extensions

Confirmed Media Router is disabled

example	example	example

Case 3: Existing profile has Media Cast ON => nothing changes

1. installed 1.66.110
2. launched Brave
3. opened brave://settings/extensions
4. toggled On Media router
5. closed the browser and renamed the profile to brave-browser-beta
6. installed 1.67.86
7. launched Brave
8. opened brave://settings/extensions

• Confirmed Media Router stayed enabled
• Confirmed Cast option in the Share menu is shown

example	example	example	example

[MadhaviSeelam]

Verification PASSED using

Brave	1.67.94 Chromium: 125.0.6422.112 (Official Build) beta (64-bit) 
Revision	3e4d210c91412b82ad8cffca556b12bbe40ff962
OS	Linux

New Install

Case 1: New profile => Media Cast is ON

1. Install 1.67.94
2. launched Brave
3. opened brave://settings/extensions

• Confirmed Media Router is enabled by default
• Confirmed Cast option in the Share menu is shown

example	example

Upgrade

Case 2: Existing profile has Media Cast OFF => nothing changes

1. installed 1.66.115
2. launched Brave
3. opened brave://settings/extensions
4. verified Media router is disabled by default
5. closed the browser and renamed the profile to brave-browser-beta
6. installed 1.67.94
7. launched Brave
8. opened brave://settings/extensions

Confirmed Media Router is disabled

example	example	example	example	example

Case 3: Existing profile has Media Cast ON => nothing changes

1. installed 1.66.115
2. launched Brave
3. opened brave://settings/extensions
4. toggled On Media router
5. closed the browser and renamed the profile to brave-browser-beta
6. installed 1.67.94
7. launched Brave
8. opened brave://settings/extensions

• Confirmed Media Router stayed enabled
• Confirmed Cast option in the Share menu is shown

example	example	example	example	example	example	example

[stephendonner]

Verification PASSED using

Brave | 1.67.100 Chromium: 125.0.6422.112 (Official Build) beta (x86_64)
-- | --
Revision | 34fcbb6655521b55468af6c63601a8e3c5d24cd2
OS | macOS Version 14.5 (Build 23F79)

New install - PASSED

Case 1: New profile --> Media Cast is ON (default)

Steps:

1. installed 1.67.100
2. launched Brave
3. opened brave://settings/extensions
4. confirmed Media Router was defaulted to Enabled / ON
5. loaded youtube.com
6. loaded a video
7. clicked on the Share button in the URL bar
8. confirmed I saw multiple Cast-enabled streaming devices from my home network
9. selected my Samsung TV

Confirmed I could cast my YouTube video to my Samsung TV

example	example	example	example	example

Upgrade - PASSED

Case 2: Existing profile has Media Cast OFF => nothing changes

Steps:

1. installed 1.66.115
2. launched Brave
3. opened brave://settings/extensions
4. verified Media Router is disabled by default
5. closed the browser and renamed the profile to Brave-Browser-Beta via mv /Users/sdonner/Library/Application\ Support/BraveSoftware/Brave-Browser /Users/sdonner/Library/Application\ Support/BraveSoftware/Brave-Browser-Beta
6. installed 1.67.100
7. launched Brave
8. opened brave://settings/extensions
9. confirmed Media Router was still Disabled / OFF
10. loaded a video on youtube.com
11. click on the Share this page icon in the URL bar

Confirmed no Cast options

example	example	example	example	example	example

Case 3: Existing profile has Media Cast ON => nothing changes

Steps:

1. installed 1.66.115
2. launched Brave
3. opened brave://settings/extensions
4. toggled On Media Router
5. restarted Brave
6. closed the browser and renamed the profile to Brave-Browser-Beta via mv /Users/sdonner/Library/Application\ Support/BraveSoftware/Brave-Browser /Users/sdonner/Library/Application\ Support/BraveSoftware/Brave-Browser-Beta
7. installed 1.67.100
8. launched Brave
9. opened brave://settings/extensions
10. confirmed Media Router was Enabled / ON

Confirmed I saw my usual in-home casting devices in the Share this page -> Cast dialog

example	example	example	example	example	example	example