Source Quicklinks

Adds a page action that allows cross-referencing of source files from the following open-source projects:
- Chromium
- Blink
- WebKit
- V8

Adds links between:
- Chromium code search (http://code.google.com/p/chromium/source/search), which also includes all of Chromium's dependencies (Blink, V8, etc.)
- Annotations, logs and revisions on trac.webkit.org, including a mapping from Blink to WebKit source paths
- Annotations, logs and revisions on src.chromium.org
- Annotations, logs and revisions on git.chromium.org
- Logs and revisions on code.google.com/p/v8

Also adds a "sql" search/Omnibox keyword for triggering searches in the above repositories (by contents, file name, and author).