When I search Google from Chrome's omnibox, there is an
aqs parameter embedded in the query, like
- What is the purpose of it?
- What does it contain?
- Does it (uniquely) identify the browser?
This is a tricky undocumented parameter. You will only find references for that in the Chrome(ium) developers community. My answer is based on some Google Searches only so maybe someone from inside will help further.
Finally, just to point to more background on the lack of documentation, there is this SO question and this curious comment from a Chrome developer in this thread about AQS implementation: "the comment here is both too short and confusing. Perhaps a longer explanation of what AQS is, what the constraints on it are, and why those constraints are necessary, should be added to some canonical place that talks about AQS."
That's it, if the documentation was created it's not Google findable.
No full answer, but a few things I discovered.
Edit: My guess at the time was right: https://code.google.com/p/chromium/codesearch#chromium/src/chrome/browser/autocomplete/autocomplete_controller.cc&sq=package:chromium&type=cs&l=392&rcl=1383945446
chrome://settings you can configure which search provider is used by the omnibox. The URL specified by the default Google provider in Chromium on Ubuntu is as follows:
This might provide additional detail as to what the browser sends to google.