At the core of every flagship Android phone, underneath the layers of brand-specific and device-specific extras, lies the same open-source foundation of Android, the Android Open Source Project. To help us all better understand that foundation, Google has made it possible to browse and search through Android Open Source Project code in a way that makes sense.
Google breaks down complex projects like Android and Chromium into smaller individual Git repositories, with Android having over 1500 different open source repositories. To help make the code more accessible to those outside of Google, the company offers things like Chromium Code Search. As the name suggests, the tool gives you the option to search as well as browse through the Chromium code as though it were one large repository.
[Source: 9to5Google]