One allocation for an SkData which makes a copy.

include/core/SkWeakRefCnt.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkWeakRefCnt_DEFINED
 #define SkWeakRefCnt_DEFINED
 
 #include "SkRefCnt.h"
 #include "SkThread.h"
 
 /** \class SkWeakRefCnt
 
     SkWeakRefCnt is the base class for objects that may be shared by multiple
     objects. When an existing strong owner wants to share a reference, it calls
     ref(). When a strong owner wants to release its reference, it calls
     unref(). When the shared object's strong reference count goes to zero as
     the result of an unref() call, its (virtual) weak_dispose method is called.
     It is an error for the destructor to be called explicitly (or via the
     object going out of scope on the stack or calling delete) if
     getRefCnt() > 1.
 
     In addition to strong ownership, an owner may instead obtain a weak
-    reference by calling weak_ref(). A call to weak_ref() must be balanced my a
+    reference by calling weak_ref(). A call to weak_ref() must be balanced by a
     call to weak_unref(). To obtain a strong reference from a weak reference,
     call try_ref(). If try_ref() returns true, the owner's pointer is now also
     a strong reference on which unref() must be called. Note that this does not
     affect the original weak reference, weak_unref() must still be called. When
     the weak reference count goes to zero, the object is deleted. While the
     weak reference count is positive and the strong reference count is zero the
     object still exists, but will be in the disposed state. It is up to the
     object to define what this means.
 
     Note that a strong reference implicitly implies a weak reference. As a
@@ skipping 30 matching lines @@
         SkASSERT(fWeakCnt == 1);
         fWeakCnt = 0;
 #endif
     }
 
     /** Return the weak reference count.
     */
     int32_t getWeakCnt() const { return fWeakCnt; }
 
     void validate() const {
-        SkRefCnt::validate();
+        this->INHERITED::validate();

[reed1, 2013/06/21 19:00:36]

please please please consider landing this and related changes independent of
this SkData effort. We keep iterating on SkData, but these sorts of changes are
fine, and unrelated (afaik).

         SkASSERT(fWeakCnt > 0);
     }
 
     /** Creates a strong reference from a weak reference, if possible. The
         caller must already be an owner. If try_ref() returns true the owner
         is in posession of an additional strong reference. Both the original
         reference and new reference must be properly unreferenced. If try_ref()
         returns false, no strong reference could be created and the owner's
         reference is in the same state as before the call.
     */
@@ skipping 25 matching lines @@
         SkASSERT(fWeakCnt > 0);
         // Release barrier (SL/S), if not provided below.
         if (sk_atomic_dec(&fWeakCnt) == 1) {
             // Aquire barrier (L/SL), if not provided above.
             // Prevents code in destructor from happening before the decrement.
             sk_membar_aquire__after_atomic_dec();
 #ifdef SK_DEBUG
             // so our destructor won't complain
             fWeakCnt = 1;
 #endif
-            SkRefCnt::internal_dispose();
+            this->INHERITED::internal_dispose();
         }
     }
 
     /** Returns true if there are no strong references to the object. When this
         is the case all future calls to try_ref() will return false.
     */
     bool weak_expired() const {
         return fRefCnt == 0;
     }
 
@@ skipping 16 matching lines @@
         weak_unref();
     }
 
     /* Invariant: fWeakCnt = #weak + (fRefCnt > 0 ? 1 : 0) */
     mutable int32_t fWeakCnt;
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif