One obvious benefit of the internal tools at Google is that they're all integrated with each other. So any Googler can quickly:

1. Search another team's code

2. Quickly jump into a Cloud IDE to make a change

3. Build and test the code, because everyone uses one build system

4. Send that code off for review and have the review tool automatically select the right reviewers and run the right tests

For a simple change (let's say a typo fix) all of the above can happen in a single browser tab in under 5 minutes even if you've never been in that part of the code before.

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While I'm here a shameless but relevant plug: if you're looking for a Google-like code review experience on GitHub check out https://codeapprove.com