Reimplement gpu message bus for invalidated bitmap gen IDs

src/gpu/GrGpuResourceCacheAccess.h

Index: src/gpu/GrGpuResourceCacheAccess.h
diff --git a/src/gpu/GrGpuResourceCacheAccess.h b/src/gpu/GrGpuResourceCacheAccess.h
index 867252d7834a2d8331a163c6bd9ff4f2c573a84c..6c99d08e469769df92ef570863e3b8cedcd9a67f 100644
--- a/src/gpu/GrGpuResourceCacheAccess.h
+++ b/src/gpu/GrGpuResourceCacheAccess.h
@@ -28,6 +28,8 @@ public:
         return fResource->setContentKey(contentKey);
     }
 
+    void removeContentKey() { return fResource->removeContentKey(); }
+
     /**
      * Is the resource currently cached as scratch? This means it is cached, has a valid scratch
      * key, and does not have a content key.