Show user data dialog earlier on Windows.

chrome/browser/ui/user_data_dir_dialog.h

Index: chrome/browser/ui/user_data_dir_dialog.h
diff --git a/chrome/browser/ui/user_data_dir_dialog.h b/chrome/browser/ui/user_data_dir_dialog.h
index eb8418ed79247fdba7946267eafb5fed58fae357..21d251b2adcf3c143a6321de13068920488d555c 100644
--- a/chrome/browser/ui/user_data_dir_dialog.h
+++ b/chrome/browser/ui/user_data_dir_dialog.h
@@ -5,6 +5,8 @@
 #ifndef CHROME_BROWSER_UI_USER_DATA_DIR_DIALOG_H_
 #define CHROME_BROWSER_UI_USER_DATA_DIR_DIALOG_H_
 
+#include "base/callback.h"
+
 namespace base {
 class FilePath;
 }
@@ -17,6 +19,11 @@ namespace chrome {
 // use.
 base::FilePath ShowUserDataDirDialog(const base::FilePath& user_data_dir);
 
+// Tests can call this to install a custom callback to be called instead of
+// actually showing the dialog when ShowUserDataDirDialog() is invoked.
+void InstallCustomShowUserDataDirDialogCallbackForTest(
+    const base::Closure& callback);
+
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_UI_USER_DATA_DIR_DIALOG_H_