Backed out changeset 84df2aaf5e2a (bug 1023677)

gfx/layers/Layers.cpp

@@ -1023,14 +1023,6 @@ ContainerLayer::DefaultComputeEffectiveTransforms(const Matrix4x4& aTransformToS
 void
 ContainerLayer::DefaultComputeSupportsComponentAlphaChildren(bool* aNeedsSurfaceCopy)
 {
-  if (!(GetContentFlags() & Layer::CONTENT_COMPONENT_ALPHA_DESCENDANT)) {
-    mSupportsComponentAlphaChildren = false;
-    if (aNeedsSurfaceCopy) {
-      *aNeedsSurfaceCopy = false;
-    }
-    return;
-  }
-
   bool supportsComponentAlphaChildren = false;
   bool needsSurfaceCopy = false;
   CompositionOp blendMode = GetEffectiveMixBlendMode();

gfx/layers/Layers.h

@@ -747,29 +747,23 @@ public:
      */
     CONTENT_COMPONENT_ALPHA = 0x02,
 
-    /**
-     * If this is set then one of the descendant layers of this one has
-     * CONTENT_COMPONENT_ALPHA set.
-     */
-    CONTENT_COMPONENT_ALPHA_DESCENDANT = 0x04,
-
     /**
      * If this is set then this layer is part of a preserve-3d group, and should
      * be sorted with sibling layers that are also part of the same group.
      */
-    CONTENT_PRESERVE_3D = 0x08,
+    CONTENT_PRESERVE_3D = 0x04,
     /**
      * This indicates that the transform may be changed on during an empty
      * transaction where there is no possibility of redrawing the content, so the
      * implementation should be ready for that.
      */
-    CONTENT_MAY_CHANGE_TRANSFORM = 0x10,
+    CONTENT_MAY_CHANGE_TRANSFORM = 0x08,
 
     /**
      * Disable subpixel AA for this layer. This is used if the display isn't suited
      * for subpixel AA like hidpi or rotated content.
      */
-    CONTENT_DISABLE_SUBPIXEL_AA = 0x20
+    CONTENT_DISABLE_SUBPIXEL_AA = 0x10
   };
   /**
    * CONSTRUCTION PHASE ONLY

layout/base/FrameLayerBuilder.cpp

@@ -3081,9 +3081,7 @@ ContainerState::Finish(uint32_t* aTextContentFlags, LayerManagerData* aData)
     layer = mNewChildLayers[i];
 
     if (!layer->GetVisibleRegion().IsEmpty()) {
-      textContentFlags |=
-        layer->GetContentFlags() & (Layer::CONTENT_COMPONENT_ALPHA |
-                                    Layer::CONTENT_COMPONENT_ALPHA_DESCENDANT);
+      textContentFlags |= layer->GetContentFlags() & Layer::CONTENT_COMPONENT_ALPHA;
     }
 
     if (!layer->GetParent()) {
@@ -3456,24 +3454,13 @@ FrameLayerBuilder::BuildContainerLayerFor(nsDisplayListBuilder* aBuilder,
   } else {
     containerLayer->SetVisibleRegion(pixBounds);
   }
-
-  // CONTENT_COMPONENT_ALPHA is propogated up to the nearest CONTENT_OPAQUE
-  // ancestor so that BasicLayerManager knows when to copy the background into
-  // pushed groups. Accelerated layers managers can't necessarily do this (only
-  // when the visible region is a simple rect), so we propogate
-  // CONTENT_COMPONENT_ALPHA_DESCENDANT all the way to the root.
-  if (flags & Layer::CONTENT_COMPONENT_ALPHA) {
-    flags |= Layer::CONTENT_COMPONENT_ALPHA_DESCENDANT;
-  }
-
   // Make sure that rounding the visible region out didn't add any area
   // we won't paint
   if (aChildren.IsOpaque() && !aChildren.NeedsTransparentSurface()) {
     bounds.ScaleRoundIn(scaleParameters.mXScale, scaleParameters.mYScale);
     if (bounds.Contains(pixBounds.ToAppUnits(appUnitsPerDevPixel))) {
-      // Clear CONTENT_COMPONENT_ALPHA and add CONTENT_OPAQUE instead.
-      flags &= ~Layer::CONTENT_COMPONENT_ALPHA;
-      flags |= Layer::CONTENT_OPAQUE;
+      // Clear CONTENT_COMPONENT_ALPHA
+      flags = Layer::CONTENT_OPAQUE;
     }
   }
   containerLayer->SetContentFlags(flags);