If the icons section of the manifest specifies paths to image files with incorrect case, the extension will work in development mode on Windows/OSX (but not linux or ChromeOS) but on install will immediately fail content verification, because we don't do a case-insensitive lookup for the expected file hashes the way we do for regular files.

I've created a test extension that reproduces the problem:

https://chrome.google.com/webstore/detail/content-verification-icon/mgaengifflaoepfbnnckpdmcgdndhlpo