Update PaintLayer::needsPaintPhase flags when layer self-painting status changes

third_party/WebKit/Source/core/paint/PaintLayerPainterTest.cpp

 // Copyright 2015 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/compositing/CompositedLayerMapping.h"
 #include "core/paint/PaintControllerPaintTest.h"
 #include "platform/graphics/GraphicsContext.h"
 
 namespace blink {
 
@@ skipping 402 matching lines @@
     toHTMLElement(layerDiv.node())->setAttribute(HTMLNames::styleAttr, "position: relative");
     document().view()->updateAllLifecyclePhases();
     ASSERT_TRUE(layerDiv.hasLayer());
     PaintLayer& layer = *layerDiv.layer();
     ASSERT_TRUE(layer.isSelfPaintingLayer());
     EXPECT_TRUE(layer.needsPaintPhaseDescendantOutlines());
     EXPECT_TRUE(layer.needsPaintPhaseFloat());
     EXPECT_TRUE(layer.needsPaintPhaseDescendantBlockBackgrounds());
 }
 
+TEST_P(PaintLayerPainterTest, PaintPhasesUpdateOnBecomingSelfPainting)
+{
+    setBodyInnerHTML(
+        "<div id='will-be-self-painting' style='width: 100px; height: 100px; overflow: hidden'>"
+        "  <div>"

[pdr., 2016/04/20 23:13:39]

Why is this inner div required?

[Xianzhu, 2016/04/21 00:42:35]

Haven't looked into the root cause, but without the div the bug couldn't be
reproduced. May debug to find out how. 

[Xianzhu, 2016/04/21 01:03:41]

Without the div, the div at line 428 will be marked mayNeedPaintInvalidation
during full layout (caused by the style change) of the 'will-be-self-painting'
div.

[pdr., 2016/04/21 18:20:57]

This doesn't seem obviously wrong to me, but I think it's a sign that we don't
fully understand this change.

If this works without the div, what mechanism is merging the paint phase flags?

+        "    <div style='outline: 1px solid red; background-color: green'>outline and background</div>"
+        "  </div>"
+        "</div>");
+
+    LayoutBlock& layerDiv = *toLayoutBlock(document().getElementById("will-be-self-painting")->layoutObject());
+    ASSERT_TRUE(layerDiv.hasLayer());
+    EXPECT_FALSE(layerDiv.layer()->isSelfPaintingLayer());
+
+    PaintLayer& htmlLayer = *toLayoutBlock(document().documentElement()->layoutObject())->layer();
+    EXPECT_TRUE(htmlLayer.needsPaintPhaseDescendantOutlines());
+    EXPECT_TRUE(htmlLayer.needsPaintPhaseDescendantBlockBackgrounds());
+
+    toHTMLElement(layerDiv.node())->setAttribute(HTMLNames::styleAttr, "width: 100px; height: 100px; overflow: hidden; position: relative");
+    document().view()->updateAllLifecyclePhases();
+    PaintLayer& layer = *layerDiv.layer();
+    ASSERT_TRUE(layer.isSelfPaintingLayer());
+    EXPECT_TRUE(layer.needsPaintPhaseDescendantOutlines());
+    EXPECT_TRUE(layer.needsPaintPhaseDescendantBlockBackgrounds());
+}
+
+TEST_P(PaintLayerPainterTest, PaintPhasesUpdateOnBecomingNonSelfPainting)
+{
+    setBodyInnerHTML(
+        "<div id='will-be-non-self-painting' style='width: 100px; height: 100px; overflow: hidden; position: relative'>"
+        "  <div>"
+        "    <div style='outline: 1px solid red; background-color: green'>outline and background</div>"
+        "  </div>"
+        "</div>");
+
+    LayoutBlock& layerDiv = *toLayoutBlock(document().getElementById("will-be-non-self-painting")->layoutObject());
+    ASSERT_TRUE(layerDiv.hasLayer());
+    PaintLayer& layer = *layerDiv.layer();
+    EXPECT_TRUE(layer.isSelfPaintingLayer());
+    EXPECT_TRUE(layer.needsPaintPhaseDescendantOutlines());
+    EXPECT_TRUE(layer.needsPaintPhaseDescendantBlockBackgrounds());
+
+    PaintLayer& htmlLayer = *toLayoutBlock(document().documentElement()->layoutObject())->layer();
+    EXPECT_FALSE(htmlLayer.needsPaintPhaseDescendantOutlines());
+    EXPECT_FALSE(htmlLayer.needsPaintPhaseDescendantBlockBackgrounds());
+
+    toHTMLElement(layerDiv.node())->setAttribute(HTMLNames::styleAttr, "width: 100px; height: 100px; overflow: hidden");
+    document().view()->updateAllLifecyclePhases();
+    EXPECT_FALSE(layer.isSelfPaintingLayer());
+    EXPECT_TRUE(htmlLayer.needsPaintPhaseDescendantOutlines());
+    EXPECT_TRUE(htmlLayer.needsPaintPhaseDescendantBlockBackgrounds());
+}
+
 } // namespace blink