Componentize chrome/common/sync_util

The file chrome/common/sync_util.cc/h and chrome/common/sync_util_unittest.cc moved to
components/sync_driver/.

Moved switches::kSyncServiceURL new file components/sync_driver/sync_driver_switch.cc.

Added extra param version_info::Channel to
--  GetSyncServiceURL ()
--  MakeDesktopUserAgentForSync()
--  MakeUserAgentForSync ()

BUG=519578

Review URL: https://codereview.chromium.org/1308313003

Cr-Commit-Position: refs/heads/master@{#346600}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 5a5332d..d6dfa41 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -36,6 +36,7 @@
 #include "components/plugins/common/plugins_switches.h"
 #include "components/proximity_auth/switches.h"
 #include "components/search/search_switches.h"
+#include "components/sync_driver/sync_driver_switches.h"
 #include "components/version_info/version_info.h"
 #include "content/public/browser/user_metrics.h"
 #include "media/base/media_switches.h"