Google Chrome 46 (stable) has been behaving weirdly recently, it is showing black boxes on parts of a web page, this was also reported by few users in forums. The problem is not OS- specific, both Windows and Mac users are experiencing this. Restarting the browser may help for a short period of time, they may re-appear again, follow the solution below until Google fixes it.
Fix Chrome Shows black boxes on web pages
To fix this
1. Ensure you’ve the latest Chrome version installed on your computer
2. Turn on the Hardware Acceleration option in Settings if disabled. For that, click on Chrome menu, select Settings > Advanced Settings, Scroll down under system, check ‘Use Hardware Acceleration when available’
3. Find and enable this flag in Chrome: Enable slimming paint phase 2.
4. If you’ve HWA already enabled, see if disabling could help the issue to go away.
6. Create a new Chrome Profile and see if the issue persists.
7. Scan your computer with Malwarebytes and remove threats, if any, found, malware might also cause this to happen.
If nothing helps, switch to beta version or Canary or another browser, or wait for the Google to fix this, this could be a bug (has been already submitted).