Push wallet result to UI side in extension observer: OnWalletInitialized

[jasonrsadler]

Follow up from brave/brave-core#2097

Description

extension observer method OnWalletInitialized is iterating on wallet creation result on native side. We would like this result to be pushed to client side code and iterated there.

Function in question: https://github.com/brave/brave-core/blob/master/components/brave_rewards/browser/extension_rewards_service_observer.cc#L29-L55

Steps to Reproduce

Actual result:

Expected result:

Reproduces how often:

Brave version (brave://version info)

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds?

Website problems only:

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

Additional Information

dev issue

[GeetaSarvadnya]

Verification passed on

Brave	0.65.93 Chromium: 74.0.3729.131 (Official Build) beta (64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Windows 10 OS Build 17134.523

• Verified the test plan from Extension observer comparison code is now moved to front side brave-core#2233

Verified passed with

Brave	0.65.97 Chromium: 74.0.3729.131 (Official Build) beta(64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Mac OS X

• Verified test plan from Extension observer comparison code is now moved to front side brave-core#2233
• Test Case 2 - Verified when internet was reconnected, I was able to join Rewards
• Test Case 3 - Verified after launching the profile specified, I was able to join Rewards from panel.

Verification passed on

Brave	0.65.97 Chromium: 74.0.3729.131 (Official Build) beta(64-bit)
Revision	518a41c1fa7ce1c8bb5e22346e82e42b4d76a96f-refs/branch-heads/3729@{#954}
OS	Ubuntu 18.04 LTS

• Verified the test plan from Extension observer comparison code is now moved to front side brave-core#2233