Support null language for fallbackFontForChar's IPC wrapper

content/common/child_process_sandbox_support_impl_linux.cc

Index: content/common/child_process_sandbox_support_impl_linux.cc
diff --git a/content/common/child_process_sandbox_support_impl_linux.cc b/content/common/child_process_sandbox_support_impl_linux.cc
index 2469ba73243fc05020fa5bc4730b77e510fadaa4..a63974c46b83079d7583c09ffbb77d3034267f07 100644
--- a/content/common/child_process_sandbox_support_impl_linux.cc
+++ b/content/common/child_process_sandbox_support_impl_linux.cc
@@ -28,7 +28,11 @@ void GetFallbackFontForCharacter(int32_t character,
   Pickle request;
   request.WriteInt(LinuxSandbox::METHOD_GET_FALLBACK_FONT_FOR_CHAR);
   request.WriteInt(character);
-  request.WriteString(preferred_locale);
+  if (preferred_locale) {
+    request.WriteBool(true);
+    request.WriteString(preferred_locale);
+  } else
+    request.WriteBool(false);
 
   uint8_t buf[512];
   const ssize_t n = UnixDomainSocket::SendRecvMsg(GetSandboxFD(), buf,