Currently in Firefox, the current domain is colored black in the URL bar, and the rest of the URL is in grey. The reason for this emphasis is to make the relevant and readable part of the URL - the domain itself - pop out and be scannable by users. While other parts of the URL may contain useful information, the domain is the most likely to be both 1. readable and 2. relevant, and thus is colored black. However, there's another portion of the URL that can be guaranteed to be human-readable: the user's search string. If a user searches for string "foo" on google.com, the resulting URL will contain at least two human-readable strings: the domain ("google.com") and the search query ("foo"). We should treat the search query identically to domains, making them black and scannable. Note: This bug is the engineering counterpart of bug 1029848. Future improvements to the URL bar of search queries to make search more readable will follow but are out of scope for this bug. Acceptance criteria: 1. The user's search query is colored black in the URL bar.

Just to reiterate what's on bug 958199#c6, this patch shouldn't change the behavior of the URL once it's focused or clicked.

Afaict, this is fixed by its dependent implementation bugs.