1 files changed, 33 insertions, 0 deletions
diff --git a/layout/base/nsIPercentBSizeObserver.h b/layout/base/nsIPercentBSizeObserver.h
new file mode 100644
index 0000000000..f11e1e2774
--- /dev/null
+++ b/layout/base/nsIPercentBSizeObserver.h
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef nsIPercentBSizeObserver_h___
+#define nsIPercentBSizeObserver_h___
+
+#include "nsQueryFrame.h"
+
+namespace mozilla {
+struct ReflowInput;
+}  // namespace mozilla
+
+/**
+ * This interface is supported by frames that need to provide computed bsize
+ * values to children during reflow which would otherwise not happen. Currently
+ * only table cells support this.
+ */
+class nsIPercentBSizeObserver {
+ public:
+  NS_DECL_QUERYFRAME_TARGET(nsIPercentBSizeObserver)
+
+  // Notify the observer that aReflowInput has no computed bsize,
+  // but it has a percent bsize
+  virtual void NotifyPercentBSize(const mozilla::ReflowInput& aReflowInput) = 0;
+
+  // Ask the observer if it should observe aReflowInput.frame
+  virtual bool NeedsToObserve(const mozilla::ReflowInput& aReflowInput) = 0;
+};
+
+#endif  // nsIPercentBSizeObserver_h___