import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

layout/base/nsIPercentBSizeObserver.h

@@ -0,0 +1,33 @@
+/* -*- 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/. */
+
+#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___