Chrome extension help

I want to notify an use开发者_运维知识库r using Chrome browser. I need something powerful like changing the Chrome skin colour, highlighting things or at the least like this extension putting an icon on the address bar https://chrome.google.com/extensions/detail/jhejngphiacapbgllhagbpdkkdieeaej

Can someone please help?

Edit:

Q1, can I change the theme when a new tab or new chrome window is open? Like the change in incognito mode?

Q2, How do I put an image on the address bar like flag fox?

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A1: No you cannot. The user must agree to changing their theme. Imagine if an extension switched your theme to show "inappropriate" content.

A2: Use page actions. https://developer.chrome.com/extensions/pageAction