Blimp: change logger to use switch/case for types.

blimp/common/proto/render_widget.proto

Index: blimp/common/proto/render_widget.proto
diff --git a/blimp/common/proto/render_widget.proto b/blimp/common/proto/render_widget.proto
index 5d34be3df9784a907d195e6bae6aa87d9599b857..1ff94e4f9e54b0a790941f63b81738fbeeb31e0e 100644
--- a/blimp/common/proto/render_widget.proto
+++ b/blimp/common/proto/render_widget.proto
@@ -11,12 +11,14 @@ package blimp;
 
 message RenderWidgetMessage {
   enum Type {
+    UNKNOWN = 0;
+
     // Engine => Client types.
     INITIALIZE = 1;
     CREATED = 2;
     DELETED = 3;
   }
 
-  optional Type type = 1;
+  optional Type type = 1 [default = UNKNOWN];
   optional int32 render_widget_id = 2;
-}
+}