Add --enable-sync-dictionary flag

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
diff --git a/chrome/common/chrome_switches.cc b/chrome/common/chrome_switches.cc
index 9bc5ccfa1369ad694e9d49e7bc84770e8818a4a0..f5c0190d900d4a52d36f152db8e08ee00ddb15c5 100644
--- a/chrome/common/chrome_switches.cc
+++ b/chrome/common/chrome_switches.cc
@@ -646,6 +646,9 @@ const char kEnableStackedTabStrip[]         = "enable-stacked-tab-strip";
 // Enables experimental suggestions pane in New Tab page.
 const char kEnableSuggestionsTabPage[]      = "enable-suggestions-ntp";
 
+// Enables syncing of dictionary.
+const char kEnableSyncDictionary[] = "enable-sync-dictionary";
+
 // Enables context menu for selecting groups of tabs.
 const char kEnableTabGroupsContextMenu[]    = "enable-tab-groups-context-menu";