Use SkLayerDrawLooper::Builder to construct SkLayerDrawLooper.

Source/platform/graphics/DrawLooper.h

Index: Source/platform/graphics/DrawLooper.h
diff --git a/Source/platform/graphics/DrawLooper.h b/Source/platform/graphics/DrawLooper.h
index 4a66910c30029162ca8768a7cc52f49b3dc366f8..67d0542a6c85374c598678022c4e2e4184de517d 100644
--- a/Source/platform/graphics/DrawLooper.h
+++ b/Source/platform/graphics/DrawLooper.h
@@ -32,11 +32,12 @@
 #define DrawLooper_h
 
 #include "platform/PlatformExport.h"
+#include "third_party/skia/include/effects/SkLayerDrawLooper.h"
 #include "wtf/Noncopyable.h"
-#include "wtf/RefPtr.h"
+#include "wtf/OwnPtr.h"
+#include "wtf/PassOwnPtr.h"
 
 class SkDrawLooper;
-class SkLayerDrawLooper;
 
 namespace WebCore {
 
@@ -58,20 +59,33 @@ public:
         ShadowIgnoresAlpha
     };
 
-    DrawLooper();
     ~DrawLooper();
 
     // Callees should not modify this looper other than to iterate over it.
     // A downcast to SkLayerDrawLooper* is tantamount to a const_cast.
     SkDrawLooper* skDrawLooper() const;
 
-    void addUnmodifiedContent();
-    void addShadow(const FloatSize& offset, float blur, const Color&,
-        ShadowTransformMode = ShadowRespectsTransforms,
-        ShadowAlphaMode = ShadowRespectsAlpha);
+    class Builder {
+    public:
+        Builder() { }
+        ~Builder() { }
+
+        void addUnmodifiedContent();
+        void addShadow(const FloatSize& offset, float blur, const Color&,
+            ShadowTransformMode = ShadowRespectsTransforms,
+            ShadowAlphaMode = ShadowRespectsAlpha);
+
+        // Pass layers to new DrawLooper object and return it. The builder
+        // should not be used any more after calling this method.
+        PassOwnPtr<DrawLooper> detachDrawLooper();
+
+    private:
+        SkLayerDrawLooper::Builder m_skDrawLooperBuilder;
+    };
 
 private:
-    RefPtr<SkLayerDrawLooper> m_skDrawLooper;
+    DrawLooper(PassOwnPtr<SkDrawLooper>);
+    OwnPtr<SkDrawLooper> m_skDrawLooper;

[jbroman, 2014/02/24 18:53:38]

I'm sorry I wasn't clear enough before, but while WebCore::DrawLooper is now not
refcounted (and so can be held with an OwnPtr), SkDrawLooper is still refcounted
(so it should be held with RefPtr here, and the constructor argument should be a
PassRefPtr).

[Dominik Grewe, 2014/02/24 19:41:03]

Of course, sorry. Wasn't thinking properly ;) Will fix it tomorrow.

 };
 
 } // namespace WebCore