[REG 5.15] PDF viewer is not working

[2348610:2348610:0513/103233.267730:FATAL:values.cc(224)] Check failed: IsStringUTF8(string_value_). #0 0x7f204315cded base::debug::CollectStackTrace()#1 0x7f2042f44a2b base::debug::StackTrace::StackTrace()#2 0x7f2042f449e2 base::debug::StackTrace::StackTrace()#3 0x7f2042f7288e logging::LogMessage::~LogMessage()#4 0x7f204314fdcc base::Value::Value()#5 0x7f204314fca7 base::Value::Value()#6 0x7f20425769fc std::make_unique<>()#7 0x7f2043156b8c base::DictionaryValue::SetString()#8 0x7f204244792d extensions::ExtensionsGuestViewMessageFilter::CreateMimeHandlerViewGuestOnUIThread()