Use skia::RefPtr to avoid having to manually refcount GraphicsContextState::m_looper.

Source/core/platform/graphics/GraphicsContext.h

Index: Source/core/platform/graphics/GraphicsContext.h
diff --git a/Source/core/platform/graphics/GraphicsContext.h b/Source/core/platform/graphics/GraphicsContext.h
index 8ae8bf801359bc264f24846a4a704ff07d918b58..8459d9604ddb736e4f67714e9053fd7b8055ea39 100644
--- a/Source/core/platform/graphics/GraphicsContext.h
+++ b/Source/core/platform/graphics/GraphicsContext.h
@@ -136,7 +136,7 @@ public:
     void setFillGradient(PassRefPtr<Gradient>);
     Gradient* fillGradient() const { return m_state->m_fillGradient.get(); }
 
-    SkDrawLooper* drawLooper() const { return m_state->m_looper; }
+    SkDrawLooper* drawLooper() const { return m_state->m_looper.get(); }
     SkColor effectiveStrokeColor() const { return m_state->applyAlpha(m_state->m_strokeData.color().rgb()); }
 
     int getNormalizedAlpha() const;
@@ -394,7 +394,7 @@ private:
         return value;
     }
 
-    void setDrawLooper(SkDrawLooper* looper) { SkRefCnt_SafeAssign(m_state->m_looper, looper); }
+    void setDrawLooper(SkDrawLooper* looper) { m_state->m_looper = looper; }
 
     // Sets up the common flags on a paint for antialiasing, effects, etc.
     // This is implicitly called by setupPaintFill and setupPaintStroke, but