Remove the no longer used kPACE connection option. No functional change.

chrome/browser/io_thread.h

Index: chrome/browser/io_thread.h
diff --git a/chrome/browser/io_thread.h b/chrome/browser/io_thread.h
index ca55e19c1bd2afb51a614e7f3b3e6101935a832a..0b94438925f11c664222c3e45c5d1c86a397a03f 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -346,12 +346,6 @@ class IOThread : public content::BrowserThreadDelegate {
   static bool ShouldEnableQuicPortSelection(
       const base::CommandLine& command_line);
 
-  // Returns true if QUIC packet pacing should be negotiated during the
-  // QUIC handshake.
-  static bool ShouldEnableQuicPacing(
-      const base::CommandLine& command_line,
-      const VariationParameters& quic_trial_params);
-
   // Returns true if QUIC should always require handshake confirmation during
   // the QUIC handshake.
   static bool ShouldQuicAlwaysRequireHandshakeConfirmation(