diff --git a/mozilla/layout/base/nsIPresShell.h b/mozilla/layout/base/nsIPresShell.h
index 6b2a9c04c62..adb387b7919 100644
--- a/mozilla/layout/base/nsIPresShell.h
+++ b/mozilla/layout/base/nsIPresShell.h
@@ -180,6 +180,8 @@ public:
 
   NS_IMETHOD AppendReflowCommand(nsIReflowCommand* aReflowCommand) = 0;
 
+  NS_IMETHOD CancelReflowCommand(nsIFrame* aTargetFrame) = 0;
+
   NS_IMETHOD ProcessReflowCommands() = 0;
 
   NS_IMETHOD ClearFrameRefs(nsIFrame* aFrame) = 0;
diff --git a/mozilla/layout/base/public/nsIPresShell.h b/mozilla/layout/base/public/nsIPresShell.h
index 6b2a9c04c62..adb387b7919 100644
--- a/mozilla/layout/base/public/nsIPresShell.h
+++ b/mozilla/layout/base/public/nsIPresShell.h
@@ -180,6 +180,8 @@ public:
 
   NS_IMETHOD AppendReflowCommand(nsIReflowCommand* aReflowCommand) = 0;
 
+  NS_IMETHOD CancelReflowCommand(nsIFrame* aTargetFrame) = 0;
+
   NS_IMETHOD ProcessReflowCommands() = 0;
 
   NS_IMETHOD ClearFrameRefs(nsIFrame* aFrame) = 0;