Paint local attachment backgrounds into composited scrolling contents layer

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/LayoutBox.h"
 
 #include "core/html/HTMLElement.h"
 #include "core/layout/ImageQualityController.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace blink {
 
 class LayoutBoxTest : public RenderingTest {
 };
 
 TEST_F(LayoutBoxTest, BackgroundObscuredInRect)
 {
     setBodyInnerHTML("<style>.column { width: 295.4px; padding-left: 10.4px; } .white-background { background: red; position: relative; overflow: hidden; border-radius: 1px; }"
         ".black-background { height: 100px; background: black; color: white; } </style>"
         "<div class='column'> <div> <div id='target' class='white-background'> <div class='black-background'></div> </div> </div> </div>");
     LayoutObject* layoutObject = getLayoutObjectByElementId("target");
     ASSERT_TRUE(layoutObject);
     ASSERT_TRUE(layoutObject->backgroundIsKnownToBeObscured());
 }
 
+TEST_F(LayoutBoxTest, BackgroundRect)

[chrishtr, 2016/08/12 17:03:00]

Add more tests for other cases.

[flackr, 2016/08/16 17:52:51]

I added tests which I think cover all of the special cases - let me know if you
think I missed any.

+{
+    setBodyInnerHTML("<style>#target { background: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUg) border-box, green content-box; width: 100px; height: 100px; padding: 10px; border: 10px solid black;}</style>"
+        "<div id='target'></div>");
+    LayoutBox* layoutBox = toLayoutBox(getLayoutObjectByElementId("target"));
+    EXPECT_EQ(LayoutRect(20, 20, 100, 100), layoutBox->backgroundRect(OpaqueBackgroundRect));
+    EXPECT_EQ(LayoutRect(0, 0, 140, 140), layoutBox->backgroundRect(TranslucentBackgroundRect));
+}
+
 } // namespace blink