Ensure that we consistently check contains: paint for fixed position containment.

third_party/WebKit/Source/core/layout/MapCoordinatesTest.cpp

Index: third_party/WebKit/Source/core/layout/MapCoordinatesTest.cpp
diff --git a/third_party/WebKit/Source/core/layout/MapCoordinatesTest.cpp b/third_party/WebKit/Source/core/layout/MapCoordinatesTest.cpp
index ee06f78ae4a5b5859d0bee3a063d0764b0e2fc7f..064108300fcf568ac4496a2ca19d2634d78b2ff7 100644
--- a/third_party/WebKit/Source/core/layout/MapCoordinatesTest.cpp
+++ b/third_party/WebKit/Source/core/layout/MapCoordinatesTest.cpp
@@ -450,6 +450,76 @@ TEST_F(MapCoordinatesTest, FixedPosInFixedPos)
     EXPECT_EQ(FloatPoint(), mappedPoint);
 }
 
+TEST_F(MapCoordinatesTest, FixedPosInTransform)
+{
+    setBodyInnerHTML("<style>#container { transform: translateY(100px); position: absolute; left: 0; top: 100px; }"
+        ".fixed { position: fixed; top: 0; }"
+        ".spacer { height: 2000px; } </style>"
+        "<div id='container'><div class='fixed' id='target'></div></div>"
+        "<div class='spacer'></div>");
+
+    document().view()->setScrollPosition(DoublePoint(0.0, 50), ProgrammaticScroll);
+    document().view()->updateAllLifecyclePhases();
+    EXPECT_EQ(50, document().view()->scrollPosition().y());
+
+    LayoutBox* target = toLayoutBox(getLayoutObjectByElementId("target"));
+    LayoutBox* container = toLayoutBox(getLayoutObjectByElementId("container"));
+    LayoutBox* body = container->parentBox();
+    LayoutBox* html = body->parentBox();
+    LayoutBox* view = html->parentBox();
+    ASSERT_TRUE(view->isLayoutView());
+
+    FloatPoint mappedPoint = mapLocalToAncestor(target, view, FloatPoint());
+    EXPECT_EQ(FloatPoint(0, 100), mappedPoint);
+    mappedPoint = mapAncestorToLocal(target, view, FloatPoint(0, 100));
+    EXPECT_EQ(FloatPoint(), mappedPoint);
+
+    mappedPoint = mapLocalToAncestor(target, container, FloatPoint());
+    EXPECT_EQ(FloatPoint(0, 0), mappedPoint);
+    mappedPoint = mapAncestorToLocal(target, container, FloatPoint(0, 0));
+    EXPECT_EQ(FloatPoint(), mappedPoint);
+
+    mappedPoint = mapLocalToAncestor(container, view, FloatPoint());
+    EXPECT_EQ(FloatPoint(0, 100), mappedPoint);
+    mappedPoint = mapAncestorToLocal(container, view, FloatPoint(0, 100));
+    EXPECT_EQ(FloatPoint(), mappedPoint);
+}
+
+TEST_F(MapCoordinatesTest, FixedPosInContainPaint)
+{
+    setBodyInnerHTML("<style>#container { contain: paint; position: absolute; left: 0; top: 100px; }"
+        ".fixed { position: fixed; top: 0; }"
+        ".spacer { height: 2000px; } </style>"
+        "<div id='container'><div class='fixed' id='target'></div></div>"
+        "<div class='spacer'></div>");
+
+    document().view()->setScrollPosition(DoublePoint(0.0, 50), ProgrammaticScroll);
+    document().view()->updateAllLifecyclePhases();
+    EXPECT_EQ(50, document().view()->scrollPosition().y());
+
+    LayoutBox* target = toLayoutBox(getLayoutObjectByElementId("target"));
+    LayoutBox* container = toLayoutBox(getLayoutObjectByElementId("container"));
+    LayoutBox* body = container->parentBox();
+    LayoutBox* html = body->parentBox();
+    LayoutBox* view = html->parentBox();
+    ASSERT_TRUE(view->isLayoutView());
+
+    FloatPoint mappedPoint = mapLocalToAncestor(target, view, FloatPoint());
+    EXPECT_EQ(FloatPoint(0, 100), mappedPoint);
+    mappedPoint = mapAncestorToLocal(target, view, FloatPoint(0, 100));

[chrishtr, 2016/07/26 18:11:03]

Shouldn't this be 150px? (including scroll)

[flackr, 2016/07/26 21:06:51]

No, the fixed position #target doesn't move when you scroll so the #target is
anchored to the top of the #container (just as with fixed elements contained by
transforms).

[chrishtr, 2016/07/26 21:49:11]

But #container should move when the view is scrolled, no? And you're mapping to
view space, not container space.

[flackr, 2016/07/26 22:36:11]

view (the LayoutView) doesn't seem to refer to the viewport for the purposes of
mapping, you can tell by the container still being 100px down from the view
(despite being absolute position). I've also tested that other fixed position
items do in fact move down. Perhaps if I map to nullptr like some of the other
tests I'd get the offset from the viewport?

[chrishtr, 2016/07/26 23:24:56]

Forgot that the view is currently special and doesn't add in scroll offset.

+    EXPECT_EQ(FloatPoint(), mappedPoint);
+
+    mappedPoint = mapLocalToAncestor(target, container, FloatPoint());
+    EXPECT_EQ(FloatPoint(0, 0), mappedPoint);
+    mappedPoint = mapAncestorToLocal(target, container, FloatPoint(0, 0));
+    EXPECT_EQ(FloatPoint(), mappedPoint);
+
+    mappedPoint = mapLocalToAncestor(container, view, FloatPoint());
+    EXPECT_EQ(FloatPoint(0, 100), mappedPoint);
+    mappedPoint = mapAncestorToLocal(container, view, FloatPoint(0, 100));
+    EXPECT_EQ(FloatPoint(), mappedPoint);
+}
+
 // TODO(chrishtr): add more multi-frame tests.
 TEST_F(MapCoordinatesTest, FixedPosInIFrameWhenMainFrameScrolled)
 {