Do not show the install prompt for themes.

chrome/browser/extensions/bundle_installer.h

Index: chrome/browser/extensions/bundle_installer.h
diff --git a/chrome/browser/extensions/bundle_installer.h b/chrome/browser/extensions/bundle_installer.h
index 2a7cb0dc6e46fbe5e838673e3c8210a2a16cb6ec..40034e7e1dabb950ad10d7e244ac9623c9115cc4 100644
--- a/chrome/browser/extensions/bundle_installer.h
+++ b/chrome/browser/extensions/bundle_installer.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/memory/linked_ptr.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/string16.h"
 #include "chrome/browser/extensions/extension_install_ui.h"
 #include "chrome/browser/extensions/webstore_installer.h"
@@ -184,6 +185,9 @@ class BundleInstaller : public WebstoreInstallHelper::Delegate,
   // The profile that the bundle should be installed in.
   Profile* profile_;
 
+  // The UI that shows the confirmation prompt.
+  scoped_ptr<ExtensionInstallUI> install_ui_;
+
   Delegate* delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(BundleInstaller);