Use the same browser instance in the sync confirmation dialog.

chrome/browser/ui/webui/signin/signin_utils.cc

Index: chrome/browser/ui/webui/signin/signin_utils.cc
diff --git a/chrome/browser/ui/webui/signin/signin_utils.cc b/chrome/browser/ui/webui/signin/signin_utils.cc
index 953bdb5a8563e27038eb61122ce4153a42578919..4ebe3080f87c0bb01809b8be349848c842ca4b42 100644
--- a/chrome/browser/ui/webui/signin/signin_utils.cc
+++ b/chrome/browser/ui/webui/signin/signin_utils.cc
@@ -65,17 +65,17 @@ Browser* GetDesktopBrowser(content::WebUI* web_ui) {
   return browser;
 }
 
-void SetInitializedModalHeight(content::WebUI* web_ui,
+void SetInitializedModalHeight(Browser* browser,
+                               content::WebUI* web_ui,
                                const base::ListValue* args) {
+  if (!browser)
+    return;
+
   double height;
   const bool success = args->GetDouble(0, &height);
   DCHECK(success);
-
-  Browser* browser = GetDesktopBrowser(web_ui);
-  if (browser) {
-    browser->signin_view_controller()->SetModalSigninHeight(
-        static_cast<int>(height));
-  }
+  browser->signin_view_controller()->SetModalSigninHeight(
+      static_cast<int>(height));
 }
 
 bool IsForceSigninEnabled() {