Just a suggestion; wouldn't it be easier to use the google page and then all you have to do is click CTRL and + (plus symbol)to make it bigger and - (minus symbol) to make it smaller?
Do you have the Home button (house button) showing which will take you to the google page once you've set it up? To show it go to the top right button (three bars) > Settings > Appearance > Check: Show Home Button > Click: Change > Click: Open This Page and type in the box www.google.com or www.google.co.uk as you prefer > Click OK. If you look above the Appearance box you will see a section called On Startup you can set Chrome to open with the google page by clicking on Open A Specific Page... and clicking Set Pages and putting the Google address there or you can click on Use Current Pages and it will save the pages you opened...make sure there no other pages opened you don't want it to save.
If you want to have the Google page when you click on the New Tab button (light grey button next to open page tab at the top) you can get this extension..just click Add To Chrome;
Click the three bar button again > Tools > Extensions > New Tab Redirect > Options > In the top input box put the Google address > Click Save.
Having done these three things you will have the Google page adjustable and more accessible. This is how mine is done and seems very flexible.