Add lock to SkPDFDict

src/pdf/SkPDFTypes.h

Index: src/pdf/SkPDFTypes.h
diff --git a/src/pdf/SkPDFTypes.h b/src/pdf/SkPDFTypes.h
index 1f06c4c5fe63dc4cac3efb5991d066601ee97499..004c767843a569ac16f060e6495ac7751aa6813e 100644
--- a/src/pdf/SkPDFTypes.h
+++ b/src/pdf/SkPDFTypes.h
@@ -369,7 +369,7 @@ public:
 
     /** The size of the dictionary.
      */
-    int size() { return fValue.count(); }
+    int size() const;
 
     /** Add the value to the dictionary with the given key.  Refs value.
      *  @param key   The key for this dictionary entry.
@@ -424,28 +424,30 @@ public:
      */
     void clear();
 
+protected:
+    /** Use to remove a single key from the dictionary.
+     */
+    void remove(const char key[]);
+
+    /** Insert references to all of the key-value pairs from the other
+     *  dictionary into this one.
+     */
+    void mergeFrom(const SkPDFDict& other);
+
 private:
     struct Rec {
-      SkPDFName* key;
-      SkPDFObject* value;
+        SkPDFName* key;
+        SkPDFObject* value;
+        Rec(SkPDFName* k, SkPDFObject* v) : key(k), value(v) {}
     };
 
-public:
-    class Iter {
-    public:
-        explicit Iter(const SkPDFDict& dict);
-        SkPDFName* next(SkPDFObject** value);
-
-    private:
-        const Rec* fIter;
-        const Rec* fStop;
-    };
-
-private:
     static const int kMaxLen = 4095;
 
+    mutable SkMutex fMutex;  // protects modifications to fValue
     SkTDArray<struct Rec> fValue;
 
+    SkPDFObject* append(SkPDFName* key, SkPDFObject* value);
+
     typedef SkPDFObject INHERITED;
 };