Release Notes for v38.8.6

Fixes

• Added validation to protocol client methods to reject protocol names that do not conform to the RFC 3986 URI scheme grammar. #50157 ^{(Also in 39, 40, 41)}
• Fixed an issue where additionalData passed to app.requestSingleInstanceLock on Windows could be truncated or fail to deserialize in the primary instance's second-instance event. #50177 ^{(Also in 39, 40, 41)}
• Fixed an issue where invalid characters in custom protocol or webRequest response header values were not rejected. #50130 ^{(Also in 39, 40, 41)}
• Fixed an issue where permission and device-chooser handlers received the top-level page origin instead of the requesting subframe's origin. #50151 ^{(Also in 39, 40, 41)}