This option AllowShortLambdasOnASingleLine similar to the other AllowShort* options, but applied to C++ lambdas.
I considered making this dependent on AllowShortFunctionsOnASingleLine, but could not think of how the breaking should be behave when the option is set to Inline and InlineOnly.
I could not find a specific coding style that requires short lambdas to always break on a new line, but I do think it's fairly common practice. Also, I note that the patch: https://reviews.llvm.org/D44609 attempts to add an option to allow formatting lambda using the Allman style braces. Here is a coding style that requires Allman style braces, but allows lambdas to be on single line if they are short. So, maybe this option would be required to handle this situation?