From cc1fa1abde50e2a1004428cd6c9791dbb0a5e49f Mon Sep 17 00:00:00 2001
From: Mats Palmgren <matspal@gmail.com>
Date: Fri, 15 Mar 2013 23:32:35 +0100
Subject: [PATCH] Bug 851485 - Restoring scroll position from history should
 only suppress one scroll-to-anchor.  r=bzbarsky

---
 layout/base/nsPresShell.cpp         | 1 +
 layout/generic/nsGfxScrollFrame.h   | 6 ++++++
 layout/generic/nsIScrollableFrame.h | 6 ++++++
 3 files changed, 13 insertions(+)

diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 5540caf3290..902bd0ce87a 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -2890,6 +2890,7 @@ PresShell::GoToAnchor(const nsAString& aAnchorName, bool aScroll)
   if (rootScroll && rootScroll->DidHistoryRestore()) {
     // Scroll position restored from history trumps scrolling to anchor.
     aScroll = false;
+    rootScroll->ClearDidHistoryRestore();
   }
 
   if (content) {
diff --git a/layout/generic/nsGfxScrollFrame.h b/layout/generic/nsGfxScrollFrame.h
index 174812652fb..283ad3033bb 100644
--- a/layout/generic/nsGfxScrollFrame.h
+++ b/layout/generic/nsGfxScrollFrame.h
@@ -537,6 +537,9 @@ public:
   virtual bool DidHistoryRestore() MOZ_OVERRIDE {
     return mInner.mDidHistoryRestore;
   }
+  virtual void ClearDidHistoryRestore() MOZ_OVERRIDE {
+    mInner.mDidHistoryRestore = false;
+  }
 
   // nsIStatefulFrame
   NS_IMETHOD SaveState(nsPresState** aState) MOZ_OVERRIDE {
@@ -790,6 +793,9 @@ public:
   virtual bool DidHistoryRestore() MOZ_OVERRIDE {
     return mInner.mDidHistoryRestore;
   }
+  virtual void ClearDidHistoryRestore() MOZ_OVERRIDE {
+    mInner.mDidHistoryRestore = false;
+  }
 
   // nsIStatefulFrame
   NS_IMETHOD SaveState(nsPresState** aState) MOZ_OVERRIDE {
diff --git a/layout/generic/nsIScrollableFrame.h b/layout/generic/nsIScrollableFrame.h
index a6caced5be9..28dd88c3e00 100644
--- a/layout/generic/nsIScrollableFrame.h
+++ b/layout/generic/nsIScrollableFrame.h
@@ -237,6 +237,12 @@ public:
    * Was the current presentation state for this frame restored from history?
    */
   virtual bool DidHistoryRestore() = 0;
+  /**
+   * Clear the flag so that DidHistoryRestore() returns false until the next
+   * RestoreState call.
+   * @see nsIStatefulFrame::RestoreState
+   */
+  virtual void ClearDidHistoryRestore() = 0;
 };
 
 #endif