First pass at content shell for the Mac. Doesn't work yet.

content/shell/shell_content_browser_client.cc

Index: content/shell/shell_content_browser_client.cc
diff --git a/content/shell/shell_content_browser_client.cc b/content/shell/shell_content_browser_client.cc
index 00ea0ab5e0cb192d87cb5f00ed7485ac5d338383..2f2cd90775d01a5eb67dc8e33a79a7f9c554ac16 100644
--- a/content/shell/shell_content_browser_client.cc
+++ b/content/shell/shell_content_browser_client.cc
@@ -20,6 +20,8 @@
 #include "content/common/view_messages.h"
 #elif defined(OS_LINUX)
 #include "content/browser/tab_contents/tab_contents_view_gtk.h"
+#elif defined(OS_MACOSX)
+#include "content/browser/tab_contents/web_contents_view_mac.h"
 #endif
 
 namespace content {
@@ -47,6 +49,8 @@ WebContentsView* ShellContentBrowserClient::CreateWebContentsView(
   return new TabContentsViewWin(web_contents);
 #elif defined(OS_LINUX)
   return new TabContentsViewGtk(web_contents, NULL);
+#elif defined(OS_MACOSX)
+  return web_contents_view_mac::CreateWebContentsView(web_contents, NULL);
 #else
   return NULL;
 #endif