Remove VIEW_TYPE_WEB_CONTENTS and make default view type INVALID.

content/public/common/view_type.h

Index: content/public/common/view_type.h
diff --git a/content/public/common/view_type.h b/content/public/common/view_type.h
index f12432dc4bc3eda7f965864529dd23b769759069..9b2c92abbbf5362721e73a20174e4e893098ce32 100644
--- a/content/public/common/view_type.h
+++ b/content/public/common/view_type.h
@@ -8,13 +8,15 @@
 
 namespace content {
 
-// Indicates different types of views.
+// Icky RTTI used by a few systems to distinguish the host type of a given
+// RenderViewHost or WebContents.
+//
+// TODO(aa): Remove this and teach those systems to keep track of their own
+// data.
 enum ViewTypeValues {
   VIEW_TYPE_INVALID,
-  VIEW_TYPE_WEB_CONTENTS,
   VIEW_TYPE_INTERSTITIAL_PAGE,
   VIEW_TYPE_DEV_TOOLS_UI,
-
   VIEW_TYPE_CONTENT_END
 };