Currently the status bar color jumps to and from theme colors as they transition in the toolbar. We should smoothly animate this color like we do for the scrim:

https://codesearch.chromium.org/chromium/src/chrome/android/java/src/org/chromium/chrome/browser/ChromeActivity.java?rcl=d6f9470f4d254471a7194bde9e291c189a8709e7&l=863

It probably makes sense to do that at the same time we build the "theme color provider".