Allow GrGpuResources' unique keys to be changed.

include/gpu/GrContext.h

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrContext_DEFINED
 #define GrContext_DEFINED
 
@@ skipping 151 matching lines @@
      */
     void purgeCache();
 
     /**
      * Purge all the unlocked resources from the cache.
      * This entry point is mainly meant for timing texture uploads
      * and is not defined in normal builds of Skia.
      */
     void purgeAllUnlockedResources();
 
-    /** Sets a unique key on the resource. The resource must not already have a unique key and the
-     *  key must not already be in use for this to succeed.
+    /**
+     * Sets a unique key on the resource. Upon key collision this resource takes the place of the
+     * previous resource that had the key.
      */
-    bool addResourceToCache(const GrUniqueKey&, GrGpuResource*);
+    void addResourceToCache(const GrUniqueKey&, GrGpuResource*);
 
     /**
      * Finds a resource in the cache, based on the specified key. This is intended for use in
      * conjunction with addResourceToCache(). The return value will be NULL if not found. The
      * caller must balance with a call to unref().
      */
     GrGpuResource* findAndRefCachedResource(const GrUniqueKey&);
 
     /** Helper for casting resource to a texture. Caller must be sure that the resource cached
         with the key is either NULL or a texture and not another resource type. */
@@ skipping 641 matching lines @@
     /**
      *  This callback allows the resource cache to callback into the GrContext
      *  when the cache is still over budget after a purge.
      */
     static void OverBudgetCB(void* data);
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif