GitLab

Creates CRWTestJSWindowIdManager to enable force injection,
bypassing hasBeenInjected check in the inject method.

Moves crw_js_window_id_manager_unittest.mm out of public directory.

BUG=465898

Review URL: https://codereview.chromium.org/1129763003

Cr-Commit-Position: refs/heads/master@{#329438}