[Sync] Add favicon datatype proto support

sync/protocol/proto_enum_conversions.cc

Index: sync/protocol/proto_enum_conversions.cc
diff --git a/sync/protocol/proto_enum_conversions.cc b/sync/protocol/proto_enum_conversions.cc
index ef1d812433818ab905394f5a857110142b7af197..ffcf9f033327c08f174e1f921c155f99db336ebb 100644
--- a/sync/protocol/proto_enum_conversions.cc
+++ b/sync/protocol/proto_enum_conversions.cc
@@ -165,6 +165,19 @@ const char* GetFaviconTypeString(
   return "";
 }
 
+const char* GetIconTypeString(
+    sync_pb::FaviconData::IconType icon_type) {
+  ASSERT_ENUM_BOUNDS(sync_pb::FaviconData, IconType, FAVICON,
+                     TOUCH_PRECOMPOSED_ICON);
+  switch (icon_type) {
+    ENUM_CASE(sync_pb::FaviconData, FAVICON);
+    ENUM_CASE(sync_pb::FaviconData, TOUCH_ICON);
+    ENUM_CASE(sync_pb::FaviconData, TOUCH_PRECOMPOSED_ICON);
+  }
+  NOTREACHED();
+  return "";
+}
+
 const char* PassphraseTypeString(
     sync_pb::NigoriSpecifics::PassphraseType type) {
   ASSERT_ENUM_BOUNDS(sync_pb::NigoriSpecifics, PassphraseType,