--- a/gfx/layers/LayersLogging.cpp
+++ b/gfx/layers/LayersLogging.cpp
@@ -97,16 +97,27 @@ AppendToString(std::stringstream& aStrea
   aStream << pfx;
   aStream << nsPrintfCString(
     "(w=%f, h=%f)",
     s.width, s.height).get();
   aStream << sfx;
 }
 
 void
+AppendToString(std::stringstream& aStream, const nsSize& sz,
+               const char* pfx, const char* sfx)
+{
+  aStream << pfx;
+  aStream << nsPrintfCString(
+    "(w=%d, h=%d)",
+    sz.width, sz.height).get();
+  aStream << sfx;
+}
+
+void
 AppendToString(std::stringstream& aStream, const wr::StickyOffsetBounds& s,
                const char* pfx, const char* sfx)
 {
   aStream << pfx;
   aStream << nsPrintfCString("(min=%f max=%f)",
       s.min, s.max).get();
   aStream << sfx;
 }

--- a/gfx/layers/LayersLogging.h
+++ b/gfx/layers/LayersLogging.h
@@ -118,16 +118,20 @@ void
 AppendToString(std::stringstream& aStream, const wr::LayoutRect& r,
                const char* pfx="", const char* sfx="");
 
 void
 AppendToString(std::stringstream& aStream, const wr::LayoutSize& s,
                const char* pfx="", const char* sfx="");
 
 void
+AppendToString(std::stringstream& aStream, const nsSize& sz,
+               const char* pfx="", const char* sfx="");
+
+void
 AppendToString(std::stringstream& aStream, const wr::StickyOffsetBounds& s,
                const char* pfx="", const char* sfx="");
 
 void
 AppendToString(std::stringstream& aStream, const nsRegion& r,
                const char* pfx="", const char* sfx="");
 
 void