small fix for clip mask cache clear

src/gpu/GrDrawTarget.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 GrDrawTarget_DEFINED
 #define GrDrawTarget_DEFINED
 
@@ skipping 950 matching lines @@
     const GrContext* getContext() const { return INHERITED::getContext(); }
 
     /**
      * Clip Mask Manager(and no one else) needs to clear private stencil bits.
      * ClipTarget subclass sets clip bit in the stencil buffer. The subclass
      * is free to clear the remaining bits to zero if masked clears are more
      * expensive than clearing all bits.
      */
     virtual void clearStencilClip(const SkIRect& rect, bool insideClip, GrRenderTarget* = NULL) = 0;
 
+    /**
+     * Release any resources that are cached but not currently in use. This
+     * is intended to give an application some recourse when resources are low.
+     */
+    virtual void purgeResources() SK_OVERRIDE {
+        // The clip mask manager can rebuild all its clip masks so just
+        // get rid of them all.
+        fClipMaskManager.purgeResources();
+    };
+
 protected:
     GrClipMaskManager           fClipMaskManager;
 
 private:
     GrClipMaskManager* getClipMaskManager() { return &fClipMaskManager; }
 
     typedef GrDrawTarget INHERITED;
 };
 
 #endif