"Wrong sources.list entry or malformed file" for Chrome while using `apt-get update`

It looks like Google has discontinued support for i386, which is why this error now shows up. It looks like they have not gracefully for how their deb install has configured apt. To fix this run the following.

sudo sed -i -e 's/deb http/deb [arch=amd64] http/' "/etc/apt/sources.list.d/google-chrome.list"

Source: https://www.reddit.com/r/chrome/comments/48oje6/linux_how_to_fix_failed_to_fetch/

Edit: As has been pointed out by others, another command is needed to prevent this fix from reverting. Since this is at the top as the accepted answer I feel it should be part of this answer.

sudo sed -i -e 's/deb http/deb [arch=amd64] http/' "/opt/google/chrome/cron/google-chrome"

Also, this issue may exist if there are two files with name google.list and google-chrome.list in /etc/apt/sources.list.d directory with the similar entry like:

In google.list:

  deb http://dl.google.com/linux/chrome/deb/ stable main

In google-chrome.list:

  deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main

Then you should remove google.list file or uncomment its entry like below:

  #deb http://dl.google.com/linux/chrome/deb/ stable main

That change was reverting overnight for me. Apparently you also need to change /opt/google/chrome/cron/google-chrome

sudo sed -i -e 's/deb http/deb [arch=amd64] http/' "/opt/google/chrome/cron/google-chrome"

Note: this is only for 64-bit

Source: further down that same Reddit thread and http://www.webupd8.org/2016/03/fix-failed-to-fetch-google-chrome_3.html