1 files changed, 45 insertions, 0 deletions
diff --git a/docshell/base/nsIScrollObserver.h b/docshell/base/nsIScrollObserver.h
new file mode 100644
index 0000000000..9ff89002f0
--- /dev/null
+++ b/docshell/base/nsIScrollObserver.h
@@ -0,0 +1,45 @@
+/* -*- 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 nsIScrollObserver_h___
+#define nsIScrollObserver_h___
+
+#include "nsISupports.h"
+#include "Units.h"
+
+// Must be kept in sync with xpcom/rust/xpcom/src/interfaces/nonidl.rs
+#define NS_ISCROLLOBSERVER_IID                       \
+  {                                                  \
+    0xaa5026eb, 0x2f88, 0x4026, {                    \
+      0xa4, 0x6b, 0xf4, 0x59, 0x6b, 0x4e, 0xdf, 0x00 \
+    }                                                \
+  }
+
+class nsIScrollObserver : public nsISupports {
+ public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISCROLLOBSERVER_IID)
+
+  /**
+   * Called when the scroll position of some element has changed.
+   */
+  virtual void ScrollPositionChanged() = 0;
+
+  /**
+   * Called when an async panning/zooming transform has started being applied
+   * and passed the scroll offset
+   */
+  MOZ_CAN_RUN_SCRIPT virtual void AsyncPanZoomStarted(){};
+
+  /**
+   * Called when an async panning/zooming transform is no longer applied
+   * and passed the scroll offset
+   */
+  MOZ_CAN_RUN_SCRIPT virtual void AsyncPanZoomStopped(){};
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsIScrollObserver, NS_ISCROLLOBSERVER_IID)
+
+#endif /* nsIScrollObserver_h___ */