Unpack theme data from extensions off of UI thread.

chrome/browser/extensions/theme_installed_infobar_delegate.cc

Index: chrome/browser/extensions/theme_installed_infobar_delegate.cc
diff --git a/chrome/browser/extensions/theme_installed_infobar_delegate.cc b/chrome/browser/extensions/theme_installed_infobar_delegate.cc
index 16d349d5a772d0060b9f1a7631f82d293147ea64..e432bbdc5b22d4b35fd8a9d4dbb7c7656a69224c 100644
--- a/chrome/browser/extensions/theme_installed_infobar_delegate.cc
+++ b/chrome/browser/extensions/theme_installed_infobar_delegate.cc
@@ -144,7 +144,9 @@ bool ThemeInstalledInfoBarDelegate::Cancel() {
     const extensions::Extension* previous_theme =
         extension_service_->GetExtensionById(previous_theme_id_, true);
     if (previous_theme) {
-      theme_service_->SetTheme(previous_theme);
+      theme_service_->RevertToTheme(previous_theme);
+      // TODO(estade): while we're waiting to close, it would be nice to
+      // indicate that the theme is busy reverting.
       return false;  // The theme change will close us.
     }
   }