To provide suggestions and search results more quickly, Chrome may preconnect to your default search engine in the background.
If the "Autocomplete searches and URLs" setting is enabled, when you focus or type in the address bar, Chrome sends data to your default search engine. As you type, the text is sent to provide suggestions to autocomplete your search queries. In addition, your IP address, search information stored on your computer as “cookies,” and the current URL, if Google is your default search engine and you sync your history to your Google Account, are all sent to find the most relevant suggestions.
If the "Help improve Chrome's features and performance" setting is enabled, Chrome also sends data back to Google to improve the suggestion feature. When you select a suggestion, Chrome sends information about the selected suggestion such as whether it was a search or a URL, how many characters you typed before you selected it and its position in the list of results. The data sent doesn't include exactly what you type or the URL you select.
If your default search engine isn't Google, your requests for suggestions and search queries are logged under that search engine's privacy policy.