UserAgent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3534.4 Safari/537.36

Steps to reproduce the problem:
1. Generate a decently sized ExtensionSettings policy with a few hundred extensions worth of policy.
2. As JSON, you will end up with a very repetitive file which is a few megabytes in size.
3. Place this into the registry on Windows or converted into a configuration profile on macOS.

What is the expected behavior?
It should be possible to craft an advanced policy using ExtensionSettings which is actually deployable.

What went wrong?
These policies end up being way too large for the places which they end up in, and cause the operating systems to have performance issues. 

On macOS, the configuration profile which I generated for this policy is in the ~5MB range, which will install, but causes the Profiles pane in System Preferences to hang for 60+ seconds when trying to preview the profile.  Other profiles interactions are hindered as well.

On Windows, registry strings have been traditionally 1MB, but can now be bigger https://docs.microsoft.com/en-us/windows/desktop/sysinfo/registry-element-size-limits.  Even so, Microsoft states "Long values (more than 2,048 bytes) should be stored in a file, and the location of the file should be stored in the registry. This helps the registry perform efficiently."

With policy sizes being this large, it becomes very hard for us to actually use them.

Did this work before? N/A 

Chrome version: 70.0.3534.4  Channel: dev
OS Version: OS X 10.14.0
Flash Version: 

This is highly compressible data - my policy is able to compress to about 2% of its original size.  While it might hurt a bit of transparency, I think that a good option here would be to support this key as Base64 gzip compressed data.  This could be as a string, but could also be through the data type on macOS which is natively supported in configuration profiles.  Placing a file on the disk probably isn't the best as it wouldn't work on Chrome OS.