Forward MIME types to BrowserPlugin when a viewer is specified.

chrome/common/extensions/mime_types_handler.h

Index: chrome/common/extensions/mime_types_handler.h
diff --git a/chrome/common/extensions/mime_types_handler.h b/chrome/common/extensions/mime_types_handler.h
index 90c8f44a9060564979414a74d6f9a018401b78c5..34f586e025dee26bf4089f8007644be8e76ca1c2 100644
--- a/chrome/common/extensions/mime_types_handler.h
+++ b/chrome/common/extensions/mime_types_handler.h
@@ -41,6 +41,8 @@ class MimeTypesHandler {
   // The URL that will be used to handle MIME type requests.
   const std::string handler_url() const { return handler_url_; }
 
+  const std::set<std::string>& mime_type_set() const { return mime_type_set_; }
+
  private:
   // The id for the extension this action belongs to (as defined in the
   // extension manifest).