Chrome Extension error: “Unchecked runtime.lastError while running browserAction.setIcon: Icon invalid." -

i trying change chrome extension icon dynamically following documentation.

unfortunately, not working following code:

chrome.browseraction.seticon({path: 'my_icon.png'}); 

in console, failing following error:

unchecked runtime.lasterror while running browseraction.seticon: icon invalid. 

after reading elsewhere on web, found need specify images size either (or both) of 19x19 px or 38x38 px.

so resized icon image, , made 2 copies of follows:

• my_icon-19.png
• my_icon-38.png

now when tried following code, worked expected:

chrome.browseraction.seticon({ path: { "19": "/images/my_icon-19.png",                                        "38": "/images/my_icon-38.png" } }); 

you not need both of versions make work, following work well:

chrome.browseraction.seticon({ path: "/images/my_icon-38.png" });