Add delegate to install web_contents helpers for MimeHandlerView.

extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h

Index: extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h
diff --git a/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h b/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..ca0525abe6d5ee477355fb3b835d8d18f3d954fa
--- /dev/null
+++ b/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest_delegate.h
@@ -0,0 +1,33 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_GUEST_DELEGATE_H_
+#define EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_GUEST_DELEGATE_H_
+
+#include "base/macros.h"
+
+namespace content {
+class WebContents;
+}  // namespace content
+
+namespace extensions {
+
+// A delegate class of MimeHandlerViewGuest that are not a part of chrome.
+class MimeHandlerViewGuest;
+
+class MimeHandlerViewGuestDelegate {
+ public:
+  MimeHandlerViewGuestDelegate() {}
+  virtual ~MimeHandlerViewGuestDelegate() {}
+
+  // Attaches helpers upon initializing the WebContents.
+  virtual void AttachHelpers(content::WebContents* web_contents) {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MimeHandlerViewGuestDelegate);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_GUEST_VIEW_MIME_HANDLER_VIEW_MIME_HANDLER_VIEW_GUEST_DELEGATE_H_