Revise the behavior of "Extensions (Brave Wallet fallback)" setting

[jamesmudgett]

There are reports that Brave Wallet fallback setting "Extensions" is interfering with MM. The goal here is to detect the MM extension and avoid inserting BW as a fallback handler when the setting "Extensions" (soon to be renamed "Extensions (Brave Wallet fallback)") is enabled

For setting Extensions(BW fallback), we will only provide fallback when MM is not installed and wallet is not created.

[darkdh]

Extensions (BW fallback) will still be default value with the following exceptions:

1. If MetaMask or Phantom is installed, there will be no fallback.
2. If BW is not created, there will be no fallback.

https://bravesoftware.slack.com/archives/C023VS4HJ6Q/p1682009313520859?thread_ts=1681911651.196279&cid=C023VS4HJ6Q

[yrliou]

Assigned to @cypt4.

[bbondy]

Just noting that we'll also remove the ability for web3 apps to query public blockchain when the wallet is not created by doing this. I think this is ok, but I just wanted to note that the scope of the change goes beyond not prompting the user to setup a wallet when a dapp tries to ask for permission.

[kjozwiak]

@jamesmudgett @cypt4 @yrliou set the above as QA/Yes as it looks like we have some STR/Cases that @srirambv can run through via brave/brave-core#18172 (comment). Please change to QA/No if I'm wrong re: the above being a QA/Yes. It should also get checked as there's associated uplifts as per brave/brave-core#18228 & brave/brave-core#18229.

[yrliou]

@kjozwiak Thanks, yes it should be QA/Yes.

[kjozwiak]

The above requires 1.50.128 or higher for 1.50.x verification 👍 However, I doubt we'll have another 1.50.x release as 1.51.x is scheduled for Tuesday with C113. If we don't get a C112 update tomorrow, I'll close off the 1.50.x milestone and move this issue into 1.51.x.

[kjozwiak]

Moving this into 1.51.x as it looks like we're not going to get another 1.50.x release. The above can basically be checked with https://github.com/brave/brave-browser/releases/tag/v1.51.107 or higher as the above landed into 1.51.x ~5 days ago.

[srirambv]

Verification passed on

Brave	1.51.109 Chromium: 113.0.5672.63 (Official Build) (64-bit)
Revision	0e1a4471d5ae5bf128b1bd8f4d627c8cbd55f70c-refs/branch-heads/5672@{#912}
OS	Windows 11 Version 22H2 (Build 22621.1344)

• Verified steps from brave/brave-core#18172
• Verified when no wallet is created window.ethereum and window.solana shows as undefined
• Verified when Brave Wallet is created window.ethereum and window.solana shows isBraveWallet: true
• Verified when MetaMask is installed window.solana continues to show isBraveWallet: true
• Verified when MetaMask is installed window.ethereum doesn't show isBraveWallet: true but instead shows isMetaMask: true

29853.mp4