Add a factory function to create WebContentsView implementations.

content/browser/web_contents/web_contents_view_win.cc

Index: content/browser/web_contents/web_contents_view_win.cc
===================================================================
--- content/browser/web_contents/web_contents_view_win.cc	(revision 137865)
+++ content/browser/web_contents/web_contents_view_win.cc	(working copy)
@@ -21,6 +21,13 @@
 using content::WebContents;
 using content::WebContentsViewDelegate;
 
+namespace content {
+WebContentsView* CreateWebContentsView(WebContentsImpl* web_contents,
+                                       WebContentsViewDelegate* delegate) {
+  return new WebContentsViewWin(web_contents, delegate);
+}
+}
+
 namespace {
 
 // We need to have a parent window for the compositing code to work correctly.