Making ShowExtensionInstallDialog a callback

chrome/browser/extensions/webstore_installer.h

Index: chrome/browser/extensions/webstore_installer.h
diff --git a/chrome/browser/extensions/webstore_installer.h b/chrome/browser/extensions/webstore_installer.h
index 12064068e3aca96053b0e48260bbc672acc71018..64cef21bf367a0e53518b8f7107f6e8a639c20c9 100644
--- a/chrome/browser/extensions/webstore_installer.h
+++ b/chrome/browser/extensions/webstore_installer.h
@@ -13,6 +13,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/supports_user_data.h"
 #include "base/values.h"
+#include "chrome/browser/extensions/extension_install_prompt.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/download_item.h"
 #include "content/public/browser/notification_observer.h"
@@ -101,6 +102,9 @@ class WebstoreInstaller :public content::NotificationObserver,
     // Whether we should record an oauth2 grant for the extensions.
     bool record_oauth2_grant;
 
+    // Used to show the install dialog.
+    ExtensionInstallPrompt::ShowDialogCallback show_dialog_callback;
+
    private:
     Approval();
   };