GitLab

1. Enable SearchEngineTabHelper on Android to auto-detect and fetch OpenSearch description document.
2. Add native function to retrieve recent visited search engines.
3. Allow recent visited search engine to be selected as default search engine.

BUG=348360

Review-Url: https://codereview.chromium.org/2349473002
Cr-Commit-Position: refs/heads/master@{#419569}