Pinned tab on Google Chrome has a rippling or highlighting effect

On Google Chrome I have a tab with twitter.com on it and it's show a "rippling" effect. Here are a couple of screenshots:

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You can see the lighter area at the top of the tab to the right of the bird and then to the left.

It moves from right to left and then jumps back to the right. Why is this happening?

It also does it for the tab with Google Reader on it.

Solution 1:

This behavior happens only with pinned tabs. Some web services update the page content in real-time and the part of the update is changing the title of the window. Since the tab is pinned, there's no way for you to see the change in the title, so Chrome engineers created this subtle notification.

Solution 2:

It's hard to tell from the images you provided, but I suspect it is the notification that the tab has updated/has new content. This would especially make sense with Reader and Twitter. eg. when the Twitter page updates to say "There are __ new tweets"