* Issue #10197: Move EngineObserver and EngineMiddleware to browser-state and refactor SessionManager dependency away.
* Issue #3532: Migrate TabsUseCases to use BrowserStore exclusively.
* Issue #10209: Migrate SessionUseCases to use BrowserStore exclusively.
* Issue #3532, #10209: Migrate components to use new UseCase APIs.
* Issue #10209: Migrate UndoMiddleware to use BrowserStore.
* Issue #3532: Migrate CustomTabsUseCases to use BrowserStore.
* Issue #10211: Migrate sample-browser to not depend on browser-session.
* Issue #10209: Remove browser-session dependency.
* Issue #3532: feature-tabs: Remove browser-session dependency.
* Issue #10209: Fix UndoMiddlewareTest
* Issue #10209: Refactor SessionUseCasesTest to not use SessionManager.
* Issue #10209: Fix SessionFeatureTest.
* Refactor support-migration tests to not use SessionManager.
* Fix tests in feature-contextmenu.
* Refactor feature-recentlyclosed tests to not use SessionManager
* Refactor browser-session-storage tests to not use SessionManager
* Refactor feature-intent tests to not use SessionManager
* Refactor feature-tabs tests to not use SessionManager pt. 1
* Refactor feature-customtabs tests to not depend on browser-session.
* Make sure initial load url flags are correct
* Refactor feature-tabs tests to not use SessionManager pt. 2
* Refactor browser-state tests to not depend on browser-session.
* SearchUseCasesTest: Use addTab use case instead of addPrivateTab.
* Samples Browser: Remove unused drawable.
* Fix feature-pwa tests
* Remove browser-session.
* Make sure engine session is linked for window requests
* Make sure engine session is linked when provided with tab
* Make sure engine session is linked when provided with tab pt. 2
* Prevent engine session from being created multiple times
* Prevent engine session from being created multiple times pt. 2
* Prevent engine session from being created multiple times pt. 3
* Part 4: REFACTOR ALL THE THINGS
* Update tests.
* Add additional test for multiple CreateEngineSessionAction dispatching.
* Refactor, some docs and tests
* Fix CustomTabs tests...