Make the metro viewer responsible for relaunching browser in desktop mode.

ui/metro_viewer/metro_viewer_messages.h

Index: ui/metro_viewer/metro_viewer_messages.h
diff --git a/ui/metro_viewer/metro_viewer_messages.h b/ui/metro_viewer/metro_viewer_messages.h
index 9108620653d1652540d26fa337cf030bc08ea098..9d0111b06c629bc1b5e6f3e2837c3c490713ffa9 100644
--- a/ui/metro_viewer/metro_viewer_messages.h
+++ b/ui/metro_viewer/metro_viewer_messages.h
@@ -92,6 +92,11 @@ IPC_MESSAGE_CONTROL2(MetroViewerHostMsg_SelectFolderDone,
 
 // Messages sent from the browser to the viewer:
 
+// Requests the viewer to open a URL in desktop mode.
+IPC_MESSAGE_CONTROL2(MetroViewerHostMsg_OpenURLOnDesktop,
+                     string16,    /* shortcut */
+                     string16     /* url */);
+
 // Requests the viewer to change the pointer to a new cursor.
 IPC_MESSAGE_CONTROL1(MetroViewerHostMsg_SetCursor,
                      int64         /* cursor */);