Clean up SkString reference counting a bit.

BUG=skia:7107

Change-Id: I47072bf31b902c79dbb850179ff6d35940de3e63
Reviewed-on: https://skia-review.googlesource.com/54720
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/include/core/SkString.h b/include/core/SkString.h
index d9a922c0c3..04eb02afc0 100644
--- a/include/core/SkString.h
+++ b/include/core/SkString.h
@@ -12,6 +12,7 @@
 
 #include "../private/SkTArray.h"
 #include "SkScalar.h"
+#include "SkRefCnt.h"
 
 #include <atomic>
 #include <stdarg.h>
@@ -240,16 +241,20 @@ public:
 private:
     struct Rec {
     public:
+        Rec() = delete;
+        static sk_sp<Rec> Make(const char text[], size_t len);
         uint32_t    fLength; // logically size_t, but we want it to stay 32bits
-        std::atomic<int32_t> fRefCnt;
+        mutable std::atomic<int32_t> fRefCnt;
         char        fBeginningOfData;
 
         char* data() { return &fBeginningOfData; }
         const char* data() const { return &fBeginningOfData; }
 
-        bool unique() { return fRefCnt.load(std::memory_order_acquire) == 1; }
+        void ref() const;
+        void unref() const;
+        bool unique() const;
     };
-    Rec* fRec;
+    sk_sp<Rec> fRec;
 
 #ifdef SK_DEBUG
     void validate() const;
@@ -258,8 +263,6 @@ private:
 #endif
 
     static const Rec gEmptyRec;
-    static Rec* AllocRec(const char text[], size_t len);
-    static Rec* RefRec(Rec*);
 };
 
 /// Creates a new string and writes into it using a printf()-style format.