I've found an easy way to get half the way back - remove the annoying search field and google logo. I'm still bothered by the small thumbnails, but for now this is my suggestion:
The search bar and logo come from Google being defined as the default search provider. Change the search provider, and they go away. But what if you do want your searches to be done by Google?
Step 1: Create a file with the following text -
location.href = "https://www.google.com/search?" + location.href.split('?');
Save it as
google_redirect.html or so.
Step 2: Go to chrome://settings/searchEngines, scroll all the way down, and add the created HTML file as a new search engine. The URL should look like
<file_path> should be replaced with the path of the folder in which the HTML file is stored.
Step 3: Set the new "search engine" as your default, and you're done.
After doing the above, Chrome will not recognize Google as your search provider, and will neither show the logo nor the search bar. Since the HTML page is local, the redirection of the query to Google should be instantaneous (online redirection pages will take much longer to be reached).
Step 4: Open a new tab and zoom in to make the thumbnails larger.
The New Tab Page change is really annoying. I expect extensions that restore previous behavior to appear soon, but at this moment I found no better solution.