SkPDF: with opaque draws, treat SRC mode as SRC_OVER

src/core/SkXfermodeInterpretation.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkXfermodeInterpretation_DEFINED
+#define SkXfermodeInterpretation_DEFINED
+
+class SkPaint;
+
+/** By analyzing the paint, we may decide we can take special
+    action. This enum lists our possible actions. */

[reed1, 2015/05/27 15:45:58]

Nit: We use a diff style for comments

e.g.

/**
 * Blurb ...
 */

+enum SkXfermodeInterpretation {
+    kNormal_SkXfermodeInterpretation,      // draw normally
+    kSrcOver_SkXfermodeInterpretation,     // draw as if in srcover mode
+    kSkipDrawing_SkXfermodeInterpretation  // draw nothing
+};
+SkXfermodeInterpretation SkInterpretXfermode(const SkPaint&, bool dstIsOpaque);
+
+#endif  // SkXfermodeInterpretation_DEFINED