TabModelObserver#didSelectTab is called in more cases than when a tab is selected, for example, when a tab is opened in the background on phones (but not tablet). There is logic where the event is called that suggests that this behavior is expected, but it shouldn't be:

https://codesearch.chromium.org/chromium/src/chrome/android/java/src/org/chromium/chrome/browser/tabmodel/TabModelImpl.java?rcl=ca318fa07be3e48d5dc9a886608823a835585c69&l=490 

We should fix this so that the event is only called when a different tab is selected. This can probably be done as an ID equality check before the event is called.