add PurgeResourceCache to track leaks

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 88 matching lines @@
     static void Unlock(ID);
     static void Remove(ID);
 
     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();
+
     /**
      * 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 41 matching lines @@
      */
     size_t setSingleAllocationByteLimit(size_t maximumAllocationSize);
     size_t getSingleAllocationByteLimit() const;
     /**
      *  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);
+    }
+
     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;
 
     class Hash;
     Hash*   fHash;
 
     DiscardableFactory  fDiscardableFactory;
     // the allocator is NULL or one that matches discardables
     SkBitmap::Allocator* fAllocator;
 
     size_t  fTotalBytesUsed;
     size_t  fTotalByteLimit;
     size_t  fSingleAllocationByteLimit;
     int     fCount;
 
-    void purgeAsNeeded();
+    void purgeAsNeeded(bool forcePurge = false);
 
     // linklist management
     void moveToHead(Rec*);
     void addToHead(Rec*);
     void detach(Rec*);
 
     void init();    // called by constructors
 
 #ifdef SK_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif
 };
 #endif