Bug 1382200 - Change implementation of the LayerMetricsWrapper IsScrollInfoLayer to use the metrics flag. r=botond

This also updates the WebRenderScrollDataWrapper function as it is meant
to be semantically equivalent to the LayerMetricsWrapper one, which
allows removal of a flag propagation.

MozReview-Commit-ID: 9DBx4qbhq5A

--HG--
extra : rebase_source : 3201d8a4bb7192ecdbe95983b605ac53b1a28c50

gfx/layers/LayerMetricsWrapper.h

@@ -178,13 +178,7 @@ public:
   {
     MOZ_ASSERT(IsValid());
 
-    // If we are not at the bottommost layer then it's
+    return Metrics().IsScrollInfoLayer();
-    // a stack of container layers all the way down to
-    // mLayer, which we can ignore. We only care about
-    // non-container descendants.
-    return Metrics().IsScrollable()
-        && mLayer->AsContainerLayer()
-        && !mLayer->GetFirstChild();
   }
 
   LayerMetricsWrapper GetParent() const

gfx/layers/wr/WebRenderScrollData.cpp

@@ -37,7 +37,6 @@ WebRenderLayerScrollData::Initialize(WebRenderScrollData& aOwner,
     mScrollIds.AppendElement(aOwner.AddMetadata(aLayer->GetScrollMetadata(i)));
   }
 
-  mIsScrollInfoLayer = aLayer->AsContainerLayer() && !aLayer->GetFirstChild();
   mTransform = aLayer->GetTransform();
   mTransformIsPerspective = aLayer->GetTransformIsPerspective();
   mEventRegions = aLayer->GetEventRegions();

gfx/layers/wr/WebRenderScrollData.h

@@ -52,7 +52,6 @@ public:
   const ScrollMetadata& GetScrollMetadata(const WebRenderScrollData& aOwner,
                                           size_t aIndex) const;
 
-  bool IsScrollInfoLayer() const { return mIsScrollInfoLayer; }
   gfx::Matrix4x4 GetTransform() const { return mTransform; }
   CSSTransformMatrix GetTransformTyped() const;
   bool GetTransformIsPerspective() const { return mTransformIsPerspective; }
@@ -84,7 +83,6 @@ private:
   // Various data that we collect from the Layer in Initialize(), serialize
   // over IPC, and use on the parent side in APZ.
 
-  bool mIsScrollInfoLayer;
   gfx::Matrix4x4 mTransform;
   bool mTransformIsPerspective;
   EventRegions mEventRegions;
@@ -188,7 +186,6 @@ struct ParamTraits<mozilla::layers::WebRenderLayerScrollData>
   {
     WriteParam(aMsg, aParam.mDescendantCount);
     WriteParam(aMsg, aParam.mScrollIds);
-    WriteParam(aMsg, aParam.mIsScrollInfoLayer);
     WriteParam(aMsg, aParam.mTransform);
     WriteParam(aMsg, aParam.mTransformIsPerspective);
     WriteParam(aMsg, aParam.mEventRegions);
@@ -207,7 +204,6 @@ struct ParamTraits<mozilla::layers::WebRenderLayerScrollData>
   {
     return ReadParam(aMsg, aIter, &aResult->mDescendantCount)
         && ReadParam(aMsg, aIter, &aResult->mScrollIds)
-        && ReadParam(aMsg, aIter, &aResult->mIsScrollInfoLayer)
         && ReadParam(aMsg, aIter, &aResult->mTransform)
         && ReadParam(aMsg, aIter, &aResult->mTransformIsPerspective)
         && ReadParam(aMsg, aIter, &aResult->mEventRegions)

gfx/layers/wr/WebRenderScrollDataWrapper.h

@@ -129,8 +129,7 @@ public:
   {
     MOZ_ASSERT(IsValid());
 
-    return Metrics().IsScrollable()
+    return Metrics().IsScrollInfoLayer();
-        && mLayer->IsScrollInfoLayer();
   }
 
   WebRenderScrollDataWrapper GetLastChild() const