Add getContext to GrResouce

http://codereview.appspot.com/5373106/



git-svn-id: http://skia.googlecode.com/svn/trunk@2688 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/gpu/GrResource.h b/include/gpu/GrResource.h
index 0d15fe9..e003353 100644
--- a/include/gpu/GrResource.h
+++ b/include/gpu/GrResource.h
@@ -13,6 +13,7 @@
 #include "GrRefCnt.h"
 
 class GrGpu;
+class GrContext;
 
 class GrResource : public GrRefCnt {
 public:
@@ -55,6 +56,15 @@
      */
      virtual size_t sizeInBytes() const = 0;
 
+     /**
+      * Retrieves the context that owns the resource. Note that it is possible
+      * for this to return NULL. When resources have been release()ed or
+      * abandon()ed they no longer have an unknowning context. Destroying a
+      * GrContext automatically releases all its resources.
+      */
+     const GrContext* getContext() const;
+     GrContext* getContext();
+
 protected:
 
     virtual void onRelease() = 0;