Add a blocking version of the sync promo dialog

chrome/browser/ui/webui/html_dialog_ui.h

Index: chrome/browser/ui/webui/html_dialog_ui.h
diff --git a/chrome/browser/ui/webui/html_dialog_ui.h b/chrome/browser/ui/webui/html_dialog_ui.h
index 4399a96e2a3e74051def237cccadfb7dc008bea6..751c1f7da05bb848ca62998bc739db092743741b 100644
--- a/chrome/browser/ui/webui/html_dialog_ui.h
+++ b/chrome/browser/ui/webui/html_dialog_ui.h
@@ -11,6 +11,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/string16.h"
+#include "content/public/browser/web_contents_delegate.h"
 #include "content/public/browser/web_ui_controller.h"
 #include "googleurl/src/gurl.h"
 #include "ui/base/ui_base_types.h"
@@ -79,6 +80,23 @@ class HtmlDialogUIDelegate {
   // shown (because you want to handle it yourself).
   virtual bool HandleContextMenu(const ContextMenuParams& params);
 
+  // A callback to allow the delegate to open a new URL inside |source|.
+  // On return |out_new_contents| should contain the WebContents the URL
+  // is opened in. Return false to use the default handler.
+  virtual bool HandleOpenURLFromTab(content::WebContents* source,
+                                    const content::OpenURLParams& params,
+                                    content::WebContents** out_new_contents) {
+    return false;
+  }
+
+  // A callback to create a new tab with |new_contents|. Return false to use the
+  // default handler.
+  virtual bool HandlerAddNewContents(content::WebContents* source,
+                                     content::WebContents* new_contents,
+                                     WindowOpenDisposition disposition,
+                                     const gfx::Rect& initial_pos,
+                                     bool user_gesture) { return false; }
+
   // Stores the dialog bounds.
   virtual void StoreDialogSize(const gfx::Size& dialog_size) {}