Most EarlGrey matchers should just have to match an accessibility ID, or label.

For some cases, we also need to check visibility (for cases where there may be some other element present in the hierarchy, but not tappable). For example, ShowTabsButton() in chrome_matchers.mm. For this case we need to see if we can simplify the matcher, and if not, the name should be updated.

In some cases we need extra checks, but if it affects the user, it should be reflected in the name of the method.