Requirement: Further requirements for mvp

[MasterK0927]

Relies on #90

• Investigate brave_browser_process_impl.cc
• Investigate brave_browser_main_extra_parts.cc for understanding PreMainMessageLoopRun
• Spawn the profile_picker at startup.
• Test it on onbording
• Security testing of existing implementation and gaps
• How to handle session timeout and logout user
• restoring tabs when user logs in
• Add a logout button (Might only be used to kill browser rn)

[MasterK0927]

kBrowserShowProfilePickerOnStartup is responsible for the behavior of Show on startup toggle. Its not explicitly available in Brave but in chromium, and brave is not overriding it so we don't have it in brave/ folder.

[MasterK0927]

Additionally, chrome/browser/profiles/profiles_state.cc manages all states and behaviors of the Profile Picker, including its functionality to display the Profile Picker at startup only when there is more than one profile.

This profile also manages the signin based restrictions on profiles that it puts on ChromeOS.

[MasterK0927]

@udaybansal19

Able to spawn the profile picker at startup on any number of profiles at every startup

We need to make changes in this file for it profile_picker.cc, as its a multiline change we can't have a patch for it.

[MasterK0927]

Also to add, I am able remove the checkbox that specifically allowed users to spawn profile picker on startup.