GitLab

When a navigation occurs and the omnibox is focused and fully selected,
the replacement URL should also be fully selected. OmnboxViewMac
currently does not do this.

Use the same logic from void OmniboxViewViews::Update().

This makes Mac consistent with other platforms. Adds a cross-platform
test to verify.

BUG=471635

Review URL: https://codereview.chromium.org/1144853003

Cr-Commit-Position: refs/heads/master@{#330683}