Google just recently patented its home page design. Were you able to notice it? Actually, it was their search box. As you can see, the search boxes of Google are now larger and bigger compared to what they have before.
According to Marissa Mayer of Google, when it comes to search boxes, it is better to have bigger in sizes. This allows your texts to be larger. Also, Google Suggest dropdown text is also in bigger in sizes.
Analyzing the new bigger search boxes, its effect to Google users will vary on the users themselves if they are enjoying the search experience with smaller or bigger search boxes.