diff -r 000000000000 -r 6474c204b198 layout/generic/nsIAnonymousContentCreator.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/generic/nsIAnonymousContentCreator.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,85 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * interface for rendering objects that manually create subtrees of
+ * anonymous content
+ */
+
+#ifndef nsIAnonymousContentCreator_h___
+#define nsIAnonymousContentCreator_h___
+
+#include "nsQueryFrame.h"
+#include "nsIContent.h"
+#include "nsStyleContext.h"
+#include "nsTArrayForwardDeclare.h"
+
+class nsBaseContentList;
+class nsIFrame;
+
+/**
+ * Any source for anonymous content can implement this interface to provide it.
+ * HTML frames like nsFileControlFrame currently use this.
+ *
+ * @see nsCSSFrameConstructor
+ */
+class nsIAnonymousContentCreator
+{
+public:
+  NS_DECL_QUERYFRAME_TARGET(nsIAnonymousContentCreator)
+
+  struct ContentInfo {
+    ContentInfo(nsIContent* aContent) :
+      mContent(aContent)
+    {}
+
+    ContentInfo(nsIContent* aContent, nsStyleContext* aStyleContext) :
+      mContent(aContent), mStyleContext(aStyleContext)
+    {}
+
+    nsIContent* mContent;
+    nsRefPtr<nsStyleContext> mStyleContext;
+    nsTArray<ContentInfo> mChildren;
+  };
+
+  /**
+   * Creates "native" anonymous content and adds the created content to
+   * the aElements array. None of the returned elements can be nullptr.
+   *
+   * If the anonymous content creator sets the editable flag on some
+   * of the elements that it creates, the flag will be applied to the node
+   * upon being bound to the document.
+   *
+   * @note The returned elements are owned by this object. This object is
+   *       responsible for calling UnbindFromTree on the elements it returned
+   *       from CreateAnonymousContent when appropriate (i.e. before releasing
+   *       them).
+   *
+   * @note Implementations of this method that add items to mChildren must not
+   *       hook them up to any parent since frame construction takes care of
+   *       that.
+   */
+  virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements)=0;
+
+  /**
+   * Appends "native" anonymous children created by CreateAnonymousContent()
+   * to the given content list depending on the filter.
+   *
+   * @see nsIContent::GetChildren for set of values used for filter.
+   */
+  virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
+                                        uint32_t aFilter) = 0;
+
+  /**
+   * Implementations can override this method to create special frames for the
+   * anonymous content returned from CreateAnonymousContent.
+   * By default this method returns nullptr, which means the default frame
+   * is created.
+   */
+  virtual nsIFrame* CreateFrameFor(nsIContent* aContent) { return nullptr; }
+};
+
+#endif
+