Adding functionality for purgin graphics resource handles
This will allow a fix to WebKit for preventing a crash when the graphics
context is destroyed before the GrContext

BUG=http://code.google.com/p/chromium/issues/detail?id=85309



git-svn-id: http://skia.googlecode.com/svn/trunk@1551 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/include/GrGpu.h b/gpu/include/GrGpu.h
index 574a430..5cb885a 100644
--- a/gpu/include/GrGpu.h
+++ b/gpu/include/GrGpu.h
@@ -325,7 +325,7 @@
      * Called to tell Gpu object that all GrResources have been lost and should
      * be abandoned.
      */
-    void abandonResources();
+    virtual void abandonResources();
 
     /**
      * Called to tell Gpu object to release all GrResources.