Extension objects are designed to be mostly immutable once they are created*. The ExtensionBuilder should return a const Extension to more closely match real world scenarios. If we really need it, we could introduce a BuildMutable() method to return a non-const version (but I can't think of an instance where that would be necessary).
*This is also kind of a lie, since we update permissions, but Extensions are passed as `const Extension` in the code.
Comment 1 by bugdroid1@chromium.org
, Sep 27