Increase width of viewportConstrainedNotCompositingReasons

Source/core/rendering/RenderLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 405 matching lines @@
     bool hasFilterInfo() const { return m_hasFilterInfo; }
     void setHasFilterInfo(bool hasFilterInfo) { m_hasFilterInfo = hasFilterInfo; }
 
     void updateFilters(const RenderStyle* oldStyle, const RenderStyle* newStyle);
 
     Node* enclosingElement() const;
 
     bool isInTopLayer() const;
     bool isInTopLayerSubtree() const;
 
+    // Note: this is internally stored using a minimal number of bits. Ensure
+    // that you have enough when you add to this enum!
     enum ViewportConstrainedNotCompositedReason {
         NoNotCompositedReason,
         NotCompositedForBoundsOutOfView,
         NotCompositedForNonViewContainer,
         NotCompositedForNoVisibleContent,
         NotCompositedForUnscrollableAncestors,
     };
 
-    void setViewportConstrainedNotCompositedReason(ViewportConstrainedNotCompositedReason reason) { m_compositingProperties.viewportConstrainedNotCompositedReason = reason; }
+    void setViewportConstrainedNotCompositedReason(ViewportConstrainedNotCompositedReason reason)
+    {
+        m_compositingProperties.viewportConstrainedNotCompositedReason = reason;
+        // This can fail if we forget to change the width of the viewportConstrainedNotCompositedReason
+        // when we update the enum.
+        ASSERT(viewportConstrainedNotCompositedReason() == reason);

[enne (OOO), 2014/02/28 20:28:46]

Compile assert?

+    }
+
     ViewportConstrainedNotCompositedReason viewportConstrainedNotCompositedReason() const { return static_cast<ViewportConstrainedNotCompositedReason>(m_compositingProperties.viewportConstrainedNotCompositedReason); }
 
     bool isOutOfFlowRenderFlowThread() const { return renderer()->isOutOfFlowRenderFlowThread(); }
 
     bool scrollsWithRespectTo(const RenderLayer*) const;
 
     void addLayerHitTestRects(LayerHitTestRects&) const;
 
     // Compute rects only for this layer
     void computeSelfHitTestRects(LayerHitTestRects&) const;
@@ skipping 279 matching lines @@
         bool hasNonCompositedChild : 1;
 
         // Should be for stacking contexts having unisolated blending descendants.
         bool shouldIsolateCompositedDescendants : 1;
 
         // True if this render layer just lost its grouped mapping due to the CompositedLayerMapping being destroyed,
         // and we don't yet know to what graphics layer this RenderLayer will be assigned.
         bool lostGroupedMapping : 1;
 
         // The reason, if any exists, that a fixed-position layer is chosen not to be composited.
-        unsigned viewportConstrainedNotCompositedReason : 2;
+        unsigned viewportConstrainedNotCompositedReason : 3;
 
         // Once computed, indicates all that a layer needs to become composited using the CompositingReasons enum bitfield.
         CompositingReasons compositingReasons;
 
         // Used for invalidating this layer's contents on the squashing GraphicsLayer.
         IntSize offsetFromSquashingLayerOrigin;
     };
 
     CompositingProperties m_compositingProperties;
 
@@ skipping 14 matching lines @@
 
 } // namespace WebCore
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showLayerTree(const WebCore::RenderLayer*);
 void showLayerTree(const WebCore::RenderObject*);
 #endif
 
 #endif // RenderLayer_h