When a tab is discarded (https://cs.chromium.org/chromium/src/chrome/browser/memory/tab_manager.cc?rcl=1469805843&l=665)
we delete the old web_contents and create a new one.
The issue is that with a new web_contents comes a new tabId (https://cs.chromium.org/chromium/src/chrome/browser/extensions/extension_tab_util.cc?rcl=1468509561&l=383) and the tabId should remain the same during a tab's lifetime. 

We need to deeply investigate to find a way of keeping the same tabId.