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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/243126">243126</a></dd>
<dt>Author</dt> <dd>simon.fraser@apple.com</dd>
<dt>Date</dt> <dd>2019-03-18 19:05:23 -0700 (Mon, 18 Mar 2019)</dd>
</dl>

<h3>Log Message</h3>
<pre>Scrolling state nodes should hold references to GraphicsLayers
https://bugs.webkit.org/show_bug.cgi?id=195844
<rdar://problem/48949634>

Reviewed by Tim Horton.

GraphicsLayers are refcounted, and the scrolling tree keeps GraphicsLayer pointers,
so for safely the scrolling tree should store RefPtr<GraphicsLayer> instead.

I removed the union (since it would be weird with a RefPtr and raw pointer). This code
should probably use WTF::Variant<> in future.

* page/scrolling/ScrollingStateNode.h:
(WebCore::LayerRepresentation::LayerRepresentation):
(WebCore::LayerRepresentation::operator GraphicsLayer* const):</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceWebCoreChangeLog">trunk/Source/WebCore/ChangeLog</a></li>
<li><a href="#trunkSourceWebCorepagescrollingScrollingStateNodeh">trunk/Source/WebCore/page/scrolling/ScrollingStateNode.h</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceWebCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/ChangeLog (243125 => 243126)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/ChangeLog   2019-03-19 01:58:05 UTC (rev 243125)
+++ trunk/Source/WebCore/ChangeLog      2019-03-19 02:05:23 UTC (rev 243126)
</span><span class="lines">@@ -1,3 +1,21 @@
</span><ins>+2019-03-18  Simon Fraser  <simon.fraser@apple.com>
+
+        Scrolling state nodes should hold references to GraphicsLayers
+        https://bugs.webkit.org/show_bug.cgi?id=195844
+        <rdar://problem/48949634>
+
+        Reviewed by Tim Horton.
+
+        GraphicsLayers are refcounted, and the scrolling tree keeps GraphicsLayer pointers,
+        so for safely the scrolling tree should store RefPtr<GraphicsLayer> instead.
+
+        I removed the union (since it would be weird with a RefPtr and raw pointer). This code
+        should probably use WTF::Variant<> in future.
+
+        * page/scrolling/ScrollingStateNode.h:
+        (WebCore::LayerRepresentation::LayerRepresentation):
+        (WebCore::LayerRepresentation::operator GraphicsLayer* const):
+
</ins><span class="cx"> 2019-03-18  Commit Queue  <commit-queue@webkit.org>
</span><span class="cx"> 
</span><span class="cx">         Unreviewed, rolling out r243092 and r243096.
</span></span></pre></div>
<a id="trunkSourceWebCorepagescrollingScrollingStateNodeh"></a>
<div class="modfile"><h4>Modified: trunk/Source/WebCore/page/scrolling/ScrollingStateNode.h (243125 => 243126)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/WebCore/page/scrolling/ScrollingStateNode.h 2019-03-19 01:58:05 UTC (rev 243125)
+++ trunk/Source/WebCore/page/scrolling/ScrollingStateNode.h    2019-03-19 02:05:23 UTC (rev 243126)
</span><span class="lines">@@ -58,11 +58,7 @@
</span><span class="cx">         PlatformLayerIDRepresentation
</span><span class="cx">     };
</span><span class="cx"> 
</span><del>-    LayerRepresentation()
-        : m_graphicsLayer(nullptr)
-        , m_layerID(0)
-        , m_representation(EmptyRepresentation)
-    { }
</del><ins>+    LayerRepresentation() = default;
</ins><span class="cx"> 
</span><span class="cx">     LayerRepresentation(GraphicsLayer* graphicsLayer)
</span><span class="cx">         : m_graphicsLayer(graphicsLayer)
</span><span class="lines">@@ -72,7 +68,6 @@
</span><span class="cx"> 
</span><span class="cx">     LayerRepresentation(PlatformLayer* platformLayer)
</span><span class="cx">         : m_typelessPlatformLayer(makePlatformLayerTypeless(platformLayer))
</span><del>-        , m_layerID(0)
</del><span class="cx">         , m_representation(PlatformLayerRepresentation)
</span><span class="cx">     {
</span><span class="cx">         retainPlatformLayer(m_typelessPlatformLayer);
</span><span class="lines">@@ -79,8 +74,7 @@
</span><span class="cx">     }
</span><span class="cx"> 
</span><span class="cx">     LayerRepresentation(GraphicsLayer::PlatformLayerID layerID)
</span><del>-        : m_graphicsLayer(nullptr)
-        , m_layerID(layerID)
</del><ins>+        : m_layerID(layerID)
</ins><span class="cx">         , m_representation(PlatformLayerIDRepresentation)
</span><span class="cx">     {
</span><span class="cx">     }
</span><span class="lines">@@ -103,7 +97,7 @@
</span><span class="cx">     operator GraphicsLayer*() const
</span><span class="cx">     {
</span><span class="cx">         ASSERT(m_representation == GraphicsLayerRepresentation);
</span><del>-        return m_graphicsLayer;
</del><ins>+        return m_graphicsLayer.get();
</ins><span class="cx">     }
</span><span class="cx"> 
</span><span class="cx">     operator PlatformLayer*() const
</span><span class="lines">@@ -179,13 +173,10 @@
</span><span class="cx">     WEBCORE_EXPORT static PlatformLayer* makePlatformLayerTyped(void* typelessPlatformLayer);
</span><span class="cx">     WEBCORE_EXPORT static void* makePlatformLayerTypeless(PlatformLayer*);
</span><span class="cx"> 
</span><del>-    union {
-        GraphicsLayer* m_graphicsLayer;
-        void* m_typelessPlatformLayer;
-    };
-
-    GraphicsLayer::PlatformLayerID m_layerID;
-    Type m_representation;
</del><ins>+    RefPtr<GraphicsLayer> m_graphicsLayer;
+    void* m_typelessPlatformLayer { nullptr };
+    GraphicsLayer::PlatformLayerID m_layerID { 0 };
+    Type m_representation { EmptyRepresentation };
</ins><span class="cx"> };
</span><span class="cx"> 
</span><span class="cx"> class ScrollingStateNode : public RefCounted<ScrollingStateNode> {
</span></span></pre>
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