From 6065102f13a612e016d999d16a0e43948b78883f Mon Sep 17 00:00:00 2001
From: Kartikaya Gupta <kgupta@mozilla.com>
Date: Wed, 21 Aug 2013 12:03:02 -0400
Subject: [PATCH] Bug 898443 - Add a parent pointer to the
 AsyncPanZoomController class. r=BenWa

---
 gfx/layers/ipc/AsyncPanZoomController.cpp |  1 +
 gfx/layers/ipc/AsyncPanZoomController.h   | 18 ++++++++++++++++--
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/gfx/layers/ipc/AsyncPanZoomController.cpp b/gfx/layers/ipc/AsyncPanZoomController.cpp
index c5d590771ad..bba94dc28bb 100644
--- a/gfx/layers/ipc/AsyncPanZoomController.cpp
+++ b/gfx/layers/ipc/AsyncPanZoomController.cpp
@@ -255,6 +255,7 @@ AsyncPanZoomController::Destroy()
   }
   mPrevSibling = nullptr;
   mLastChild = nullptr;
+  mParent = nullptr;
 }
 
 /* static */float
diff --git a/gfx/layers/ipc/AsyncPanZoomController.h b/gfx/layers/ipc/AsyncPanZoomController.h
index 9150a0c6127..1941283c7ea 100644
--- a/gfx/layers/ipc/AsyncPanZoomController.h
+++ b/gfx/layers/ipc/AsyncPanZoomController.h
@@ -616,13 +616,27 @@ private:
    * instance.
    */
 public:
-  void SetLastChild(AsyncPanZoomController* child) { mLastChild = child; }
-  void SetPrevSibling(AsyncPanZoomController* sibling) { mPrevSibling = sibling; }
+  void SetLastChild(AsyncPanZoomController* child) {
+    mLastChild = child;
+    if (child) {
+      child->mParent = this;
+    }
+  }
+
+  void SetPrevSibling(AsyncPanZoomController* sibling) {
+    mPrevSibling = sibling;
+    if (sibling) {
+      sibling->mParent = mParent;
+    }
+  }
+
   AsyncPanZoomController* GetLastChild() const { return mLastChild; }
   AsyncPanZoomController* GetPrevSibling() const { return mPrevSibling; }
+  AsyncPanZoomController* GetParent() const { return mParent; }
 private:
   nsRefPtr<AsyncPanZoomController> mLastChild;
   nsRefPtr<AsyncPanZoomController> mPrevSibling;
+  nsRefPtr<AsyncPanZoomController> mParent;
 
   /* The functions and members in this section are used to maintain the
    * area that this APZC instance is responsible for. This is used when