Let blitters be notified when they're done being used

src/core/SkBlitter.h

Index: src/core/SkBlitter.h
diff --git a/src/core/SkBlitter.h b/src/core/SkBlitter.h
index 0f1006fcfb70909e640f47b735771dea1b796e5a..8d7df76842d8c254d55c00779d204ed3abc51ee9 100644
--- a/src/core/SkBlitter.h
+++ b/src/core/SkBlitter.h
@@ -25,6 +25,7 @@
 */
 class SkBlitter {
 public:
+    SkBlitter() : fBlitMemory(NULL) { }
     virtual ~SkBlitter();
 
     /// Blit a horizontal run of one or more pixels.
@@ -76,6 +77,14 @@ public:
      */
     virtual int requestRowsPreserved() const { return 1; }
 
+    /**
+     * This function allocates memory for the blitter that the blitter then owns.
+     * The memory can be used by the calling function at will, but it will be
+     * released when the blitter's destructor is called. This function returns
+     * NULL if no persistent memory is needed by the blitter.
+     */
+    void* allocBlitMemory(size_t);
+
     ///@name non-virtual helpers
     void blitMaskRegion(const SkMask& mask, const SkRegion& clip);
     void blitRectRegion(const SkIRect& rect, const SkRegion& clip);
@@ -98,6 +107,10 @@ public:
                                    SkTBlitterAllocator*);
     ///@}
 
+protected:
+
+    void* fBlitMemory;
+    
 private:
 };