With the latest version of Chrome on Android (69) the Chrome header and Android status bar are white by default. In some cases, e.g. when you are editing an article, there is no distinction between the bottom of the status bar and the top of our website. Previously the status bar was black by default so this wasn't an issue.
As @Krinkle pointed out in T204691#5752221 there is a more optimal solution available to us: adding a gray border between the top of the website and the browser header/status bar. This will solve the issue without drawing attention to the header/status bar (as the previous solution does). The border should be 1px solid #eaecf0 and should result in the following:
We can define a theme color in our site's manifest file so the status bar and Chrome header are no longer white. Our first choice was base90/#f8f9fa, however that color doesn't seem to be registering (our assumption is that it's too light) so we'll be going with our second choice of base80/#eaecf0 instead.