Chromium change: https://chromium.googlesource.com/chromium/src/+/754d173c43ec2d98025a07946e5296828dc239cb [Reload Button] Add support to observe tab changes Observe tab changes in the ReloadButtonMediator instead of updating it from ToolbarManager. Reload state will change based on the current tab and its loading and crashed states. Reworked how reload button received updates from NTP. Previously any component could change reloading state by calling public API. Now we enforce NTP reloading state with ObservableSupplier and keeping reloading state management in a single place. Bug: 402347979