Add a blocking version of the sync promo dialog

chrome/browser/ui/browser_init.h

Index: chrome/browser/ui/browser_init.h
diff --git a/chrome/browser/ui/browser_init.h b/chrome/browser/ui/browser_init.h
index 6675ec117d265cfdd8c57d10c0edf8ca1541b4fd..ddc6e023483c99a0169539c4f3fcfca3582e48a8 100644
--- a/chrome/browser/ui/browser_init.h
+++ b/chrome/browser/ui/browser_init.h
@@ -241,6 +241,16 @@ class BrowserInit {
     // Returns true if so.
     bool CheckIfAutoLaunched(Profile* profile);
 
+    // Shows a sync promo dialog if necessary. When called |browser| should be
+    // the browser that's being used for startup. On return |browser| is set
+    // to the browser spawned from the sync promo dialog (if any). On input
+    // |tabs| should be the set of tabs to show on startup.  On return |tabs|
+    // will contain the new set of tabs to show on startup. Returns the index
+    // of the tab to activate.
+    size_t ShowSyncPromoDialog(bool process_startup,
+                               Browser** browser,
+                               std::vector<Tab>* tabs);
+
     const FilePath cur_dir_;
     const CommandLine& command_line_;
     Profile* profile_;