From 27cbe35110fa404098ef074098fd7bfc1f9d847b Mon Sep 17 00:00:00 2001
From: Alexandru Michis <malexandru@mozilla.com>
Date: Sun, 22 Aug 2021 03:15:08 +0300
Subject: [PATCH] Backed out changeset 6df43bd2a7bc (bug 1724358) for causing
 gv-junit failures in testOverscrollBehaviorNoneAuto

---
 gfx/layers/apz/src/AsyncPanZoomController.cpp |  26 ++--
 gfx/layers/apz/src/Axis.h                     |   2 -
 .../apz/test/mochitest/helper_empty.html      |   4 -
 ...ents_handoff_on_non_scrollable_iframe.html | 113 ------------------
 .../mochitest/test_group_wheelevents.html     |   1 -
 5 files changed, 10 insertions(+), 136 deletions(-)
 delete mode 100644 gfx/layers/apz/test/mochitest/helper_empty.html
 delete mode 100644 gfx/layers/apz/test/mochitest/helper_wheelevents_handoff_on_non_scrollable_iframe.html

diff --git a/gfx/layers/apz/src/AsyncPanZoomController.cpp b/gfx/layers/apz/src/AsyncPanZoomController.cpp
index f02359e87540..5e8b46ac8314 100644
--- a/gfx/layers/apz/src/AsyncPanZoomController.cpp
+++ b/gfx/layers/apz/src/AsyncPanZoomController.cpp
@@ -2181,16 +2181,10 @@ bool AsyncPanZoomController::CanScroll(const InputData& aEvent) const {
 ScrollDirections AsyncPanZoomController::GetAllowedHandoffDirections() const {
   ScrollDirections result;
   RecursiveMutexAutoLock lock(mRecursiveMutex);
-
-  // In Fission there can be non-scrollable APZCs. It's unclear whether
-  // overscroll-behavior should be respected for these
-  // (see https://github.com/w3c/csswg-drafts/issues/6523) but
-  // we currently don't, to match existing practice.
-  const bool isScrollable = mX.CanScroll() || mY.CanScroll();
-  if (!isScrollable || mX.OverscrollBehaviorAllowsHandoff()) {
+  if (mX.OverscrollBehaviorAllowsHandoff()) {
     result += ScrollDirection::eHorizontal;
   }
-  if (!isScrollable || mY.OverscrollBehaviorAllowsHandoff()) {
+  if (mY.OverscrollBehaviorAllowsHandoff()) {
     result += ScrollDirection::eVertical;
   }
   return result;
@@ -3659,14 +3653,13 @@ Maybe<CSSPoint> AsyncPanZoomController::GetCurrentAnimationDestination(
 ParentLayerPoint
 AsyncPanZoomController::AdjustHandoffVelocityForOverscrollBehavior(
     ParentLayerPoint& aHandoffVelocity) const {
-
+  RecursiveMutexAutoLock lock(mRecursiveMutex);
   ParentLayerPoint residualVelocity;
-  ScrollDirections handoffDirections = GetAllowedHandoffDirections();
-  if (!handoffDirections.contains(ScrollDirection::eHorizontal)) {
+  if (!mX.OverscrollBehaviorAllowsHandoff()) {
     residualVelocity.x = aHandoffVelocity.x;
     aHandoffVelocity.x = 0;
   }
-  if (!handoffDirections.contains(ScrollDirection::eVertical)) {
+  if (!mY.OverscrollBehaviorAllowsHandoff()) {
     residualVelocity.y = aHandoffVelocity.y;
     aHandoffVelocity.y = 0;
   }
@@ -3674,8 +3667,9 @@ AsyncPanZoomController::AdjustHandoffVelocityForOverscrollBehavior(
 }
 
 bool AsyncPanZoomController::OverscrollBehaviorAllowsSwipe() const {
+  RecursiveMutexAutoLock lock(mRecursiveMutex);
   // Swipe navigation is a "non-local" overscroll behavior like handoff.
-  return GetAllowedHandoffDirections().contains(ScrollDirection::eHorizontal);
+  return mX.OverscrollBehaviorAllowsHandoff();
 }
 
 void AsyncPanZoomController::HandleFlingOverscroll(
@@ -3799,11 +3793,11 @@ bool AsyncPanZoomController::CallDispatchScroll(
   // Obey overscroll-behavior.
   ParentLayerPoint endPoint = aEndPoint;
   if (aOverscrollHandoffState.mChainIndex > 0) {
-    ScrollDirections handoffDirections = GetAllowedHandoffDirections();
-    if (!handoffDirections.contains(ScrollDirection::eHorizontal)) {
+    RecursiveMutexAutoLock lock(mRecursiveMutex);
+    if (!mX.OverscrollBehaviorAllowsHandoff()) {
       endPoint.x = aStartPoint.x;
     }
-    if (!handoffDirections.contains(ScrollDirection::eVertical)) {
+    if (!mY.OverscrollBehaviorAllowsHandoff()) {
       endPoint.y = aStartPoint.y;
     }
     if (aStartPoint == endPoint) {
diff --git a/gfx/layers/apz/src/Axis.h b/gfx/layers/apz/src/Axis.h
index 1e313b8929fc..669d7d635dc9 100644
--- a/gfx/layers/apz/src/Axis.h
+++ b/gfx/layers/apz/src/Axis.h
@@ -368,8 +368,6 @@ class Axis {
   const FrameMetrics& GetFrameMetrics() const;
   const ScrollMetadata& GetScrollMetadata() const;
 
-  // Do not use this function directly, use
-  // AsyncPanZoomController::GetAllowedHandoffDirections instead.
   virtual OverscrollBehavior GetOverscrollBehavior() const = 0;
 
   // Adjust a requested overscroll amount for resistance, yielding a smaller
diff --git a/gfx/layers/apz/test/mochitest/helper_empty.html b/gfx/layers/apz/test/mochitest/helper_empty.html
deleted file mode 100644
index 68cd9179f55d..000000000000
--- a/gfx/layers/apz/test/mochitest/helper_empty.html
+++ /dev/null
@@ -1,4 +0,0 @@
-<!DOCTYPE html>
-<script src="apz_test_utils.js"></script>
-<script src="/tests/SimpleTest/SimpleTest.js"></script>
-<script src="/tests/SimpleTest/paint_listener.js"></script>
diff --git a/gfx/layers/apz/test/mochitest/helper_wheelevents_handoff_on_non_scrollable_iframe.html b/gfx/layers/apz/test/mochitest/helper_wheelevents_handoff_on_non_scrollable_iframe.html
deleted file mode 100644
index eec230e71dac..000000000000
--- a/gfx/layers/apz/test/mochitest/helper_wheelevents_handoff_on_non_scrollable_iframe.html
+++ /dev/null
@@ -1,113 +0,0 @@
-<!DOCTYPE HTML>
-<html>
-<head>
-  <meta charset="utf-8">
-  <title>scroll handoff on non scrollable iframe document with overscroll-behavior: none</title>
-  <script src="/tests/SimpleTest/paint_listener.js"></script>
-  <script src="apz_test_utils.js"></script>
-  <script src="apz_test_native_event_utils.js"></script>
-</head>
-<style>
-iframe {
-    width: 500px;
-    height: 500px;
-}
-</style>
-<body>
-<iframe></iframe>
-<div style="height:1000vh"></div>
-<script>
-
-// This test runs twice, with a same origin iframe first then with a cross
-// origin iframe second.
-async function test(targetOrigin) {
-  const iframe = document.querySelector("iframe");
-  const targetURL =
-    SimpleTest.getTestFileURL("helper_empty.html")
-    .replace(window.location.origin, targetOrigin);
-  iframe.src = targetURL;
-
-  await new Promise(resolve => {
-    iframe.onload = resolve;
-  });
-
-  await SpecialPowers.spawn(iframe, [], async () => {
-    content.document.documentElement.style =
-        "overscroll-behavior-y: none; overflow-y: scroll;";
-
-    // Flush the style change.
-    content.document.documentElement.getBoundingClientRect();
-    // Make sure the style change reaches to APZ.
-    await content.window.wrappedJSObject.promiseApzFlushedRepaints();
-  });
-
-  let scrollEventPromise = new Promise(resolve => {
-    window.addEventListener("scroll", resolve, { once: true });
-  });
-
-  synthesizeNativeWheel(iframe, 100, 100, 0, -10);
-  await scrollEventPromise;
-  await waitToClearOutAnyPotentialScrolls(window);
-
-  ok(window.scrollY > 0,
-     "Mouse wheel scrolling on an OOP iframe where the iframe document is " +
-     "not scrollable but has overscroll-behavior: none property should be " +
-     "handed off to the parent");
-
-  // Make sure the wheel scrolling has finished.
-  await waitToClearOutAnyPotentialScrolls(window);
-
-  // Make the iframe document scrollable and try to scroll up on the iframe
-  // document.
-  await SpecialPowers.spawn(iframe, [], async () => {
-    content.document.body.style = "height: 500vh;";
-
-    // Flush the style change.
-    content.document.documentElement.getBoundingClientRect();
-    // Make sure the style change reaches to APZ.
-    await content.window.wrappedJSObject.promiseApzFlushedRepaints();
-  });
-
-  const mousemoveEventPromise = SpecialPowers.spawn(iframe, [], async () => {
-    await new Promise(resolve => {
-      content.window.addEventListener("mousemove", resolve, { once: true });
-    });
-  });
-
-  // Make sure the above event listener is registered.
-  await SpecialPowers.spawn(iframe, [], async () => {
-    await content.window.wrappedJSObject.promiseApzFlushedRepaints();
-  });
-
-  const scrollPos = window.scrollY;
-
-  // Send a mousemove event on the iframe to finish the last wheel event block.
-  synthesizeNativeMouseEventWithAPZ({
-    type: "mousemove",
-    target: iframe,
-    offsetX: 100,
-    offsetY: 100 + scrollPos,
-  });
-  await mousemoveEventPromise;
-
-  // Try to scroll up by a new wheel event on the iframe.
-  synthesizeNativeWheel(iframe, 100, 100 + scrollPos, 0, 10);
-  await waitToClearOutAnyPotentialScrolls(window);
-
-  // The wheel event should not be handed off to the root scroller since the
-  // iframe document has `overscroll-behavior-y: none`.
-  is(window.scrollY, scrollPos,
-     "The root scroller's position should never be changed");
-
-  // Restore the root scroll position for the next test case.
-  window.scrollTo(0, 0);
-}
-
-waitUntilApzStable()
-.then(async () => test(window.location.origin))
-.then(async () => test("http://example.com/"))
-.then(subtestDone, subtestFailed);
-
-</script>
-</body>
-</html>
diff --git a/gfx/layers/apz/test/mochitest/test_group_wheelevents.html b/gfx/layers/apz/test/mochitest/test_group_wheelevents.html
index 3e1c3a2f7fd3..fd1b6e1024fc 100644
--- a/gfx/layers/apz/test/mochitest/test_group_wheelevents.html
+++ b/gfx/layers/apz/test/mochitest/test_group_wheelevents.html
@@ -43,7 +43,6 @@ var subtests = [
   {"file": "helper_scroll_over_scrollbar.html", "prefs": scrollbar_prefs},
   {"file": "helper_scroll_tables_perspective.html", "prefs": prefs},
   {"file": "helper_wheelevents_handoff_on_iframe.html", "prefs": prefs},
-  {"file": "helper_wheelevents_handoff_on_non_scrollable_iframe.html", "prefs": prefs},
 ];
 
 // Only Windows has the test api implemented for this test.