Attached ClipMaskManager to GPU resource freeing system

http://codereview.appspot.com/6208058/



git-svn-id: http://skia.googlecode.com/svn/trunk@3927 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index aeb51f8..ba73f7d 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -318,6 +318,12 @@
     // GrDrawTarget overrides
     virtual void clear(const GrIRect* rect, GrColor color);
 
+    virtual void purgeResources() SK_OVERRIDE {
+        // The clip mask manager can rebuild all its clip masks so just
+        // get rid of them all.
+        fClipMaskManager.releaseResources();
+    }
+
     // After the client interacts directly with the 3D context state the GrGpu
     // must resync its internal state and assumptions about 3D context state.
     // Each time this occurs the GrGpu bumps a timestamp.