Make SkTextBlob::RunIterator public.

src/core/SkTextBlobPriv.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 SkTextBlobPriv_DEFINED
+#define SkTextBlobPriv_DEFINED
+
+#include "SkTextBlob.h"
+
+/**
+ *  Iterate through all of the text runs of the text blob.  For example:
+ *    for (SkTextBlob::RunIterator it(blob); !it.done(); it.next()) {
+ *         .....
+ *    }
+ */
+class SkTextBlob::RunIterator {
+public:
+    RunIterator(const SkTextBlob* blob);
+    
+    bool done() const;
+    void next();
+    
+    uint32_t glyphCount() const;
+    const uint16_t* glyphs() const;
+    const SkScalar* pos() const;
+    const SkPoint& offset() const;
+    void applyFontToPaint(SkPaint*) const;
+    GlyphPositioning positioning() const;
+    bool isLCD() const;
+    
+private:
+    const RunRecord* fCurrentRun;
+    int              fRemainingRuns;
+    
+    SkDEBUGCODE(uint8_t* fStorageTop;)
+};
+
+#endif  // SkTextBlobPriv_DEFINED