private iterator to visit all resource cache entries

src/core/SkGlyphCache.h

Index: src/core/SkGlyphCache.h
diff --git a/src/core/SkGlyphCache.h b/src/core/SkGlyphCache.h
index 1c985bf6715070bd1ff520535919aec3786429d2..dc2aa579a739d10a5e6e317aa77c611d4b0ac01c 100644
--- a/src/core/SkGlyphCache.h
+++ b/src/core/SkGlyphCache.h
@@ -66,7 +66,10 @@ public:
 
     /** Returns the number of glyphs for this strike.
     */
-    unsigned getGlyphCount();
+    unsigned getGlyphCount() const;
+
+    /** Return the number of glyphs currently cached. */
+    int countCachedGlyphs() const;
 
     /** Return the image associated with the glyph. If it has not been generated this will
         trigger that.
@@ -138,6 +141,9 @@ public:
 
     static void Dump();
 
+    typedef void (*Visitor)(const SkGlyphCache&, void* context);
+    static void VisitAll(Visitor, void* context);
+
 #ifdef SK_DEBUG
     void validate() const;
 #else