allow SkBitmapCache to operate on a local instance, for testability

src/core/SkResourceCache.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 SkResourceCache_DEFINED
 #define SkResourceCache_DEFINED
 
@@ skipping 108 matching lines @@
     static size_t GetTotalBytesUsed();
     static size_t GetTotalByteLimit();
     static size_t SetTotalByteLimit(size_t newLimit);
 
     static size_t SetSingleAllocationByteLimit(size_t);
     static size_t GetSingleAllocationByteLimit();
 
     static void PurgeAll();
 
     /**
+     *  Returns the DiscardableFactory used by the global cache, or NULL.
+     */
+    static DiscardableFactory GetDiscardableFactory();
+
+    /**
      * Use this allocator for bitmaps, so they can use ashmem when available.
      * Returns NULL if the ResourceCache has not been initialized with a DiscardableFactory.
      */
     static SkBitmap::Allocator* GetAllocator();
 
     /**
      *  Call SkDebugf() with diagnostic information about the state of the cache
      */
     static void Dump();
 
@@ skipping 43 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 setTotalByteLimit(size_t newLimit);
 
     void purgeAll() {
         this->purgeAsNeeded(true);
     }
 
+    DiscardableFactory discardableFactory() const { return fDiscardableFactory; }
     SkBitmap::Allocator* allocator() const { return fAllocator; };
 
     /**
      *  Call SkDebugf() with diagnostic information about the state of the cache
      */
     void dump() const;
 
 private:
     Rec*    fHead;
     Rec*    fTail;
@@ skipping 20 matching lines @@
 
     void init();    // called by constructors
 
 #ifdef SK_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif
 };
 #endif