Don't call purgeCache() from within GrResource memebers.

src/gpu/GrResourceCache.h

Index: src/gpu/GrResourceCache.h
diff --git a/src/gpu/GrResourceCache.h b/src/gpu/GrResourceCache.h
index f05ba982316b69ed9cc68da5458bd134f28a574a..c4ead34595049d7a4d4bcf28d670a5d9e9d94f81 100644
--- a/src/gpu/GrResourceCache.h
+++ b/src/gpu/GrResourceCache.h
@@ -206,6 +206,10 @@ bool GrResourceKey::EQ(const GrResourceEntry& a, const GrResourceEntry& b) {
  *  For even faster searches, a hash is computed from the Key. If there is
  *  a collision between two keys with the same hash, we fall back on the
  *  bsearch, and update the hash to reflect the most recent Key requested.
+ *
+ *  It is a goal to make the GrResourceCache the central repository and bookkeeper
+ *  of all resources. It should replace the linked list of GrResources that
+ *  GrGpu uses to call abandon/release.
  */
 class GrResourceCache {
 public: