Trying to add the same scaled image twice shouldn't assert.

src/core/SkScaledImageCache.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkScaledImageCache_DEFINED
 #define SkScaledImageCache_DEFINED
 
@@ skipping 108 matching lines @@
 
     /**
      *  Set the maximum number of bytes available to this cache. If the current
      *  cache exceeds this new value, it will be purged to try to fit within
      *  this new limit.
      */
     size_t setByteLimit(size_t newLimit);
 
 public:
     struct Rec;
+    struct Key;
 private:
     Rec*    fHead;
     Rec*    fTail;
 
     class Hash;
     Hash*   fHash;
 
     size_t  fBytesUsed;
     size_t  fByteLimit;
     int     fCount;
 
     Rec* findAndLock(uint32_t generationID, SkScalar sx, SkScalar sy,
                      const SkIRect& bounds);
-    void addAndLock(Rec* rec);
+    Rec* findAndLock(const Key& key);
+    ID* addAndLock(Rec* rec);
 
     void purgeAsNeeded();
 
     // linklist management
     void moveToHead(Rec*);
     void addToHead(Rec*);
     void detach(Rec*);
 #ifdef SK_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif
 };
 #endif