Don't flush on read/write pixels unless necessary

include/gpu/GrGpuResource.h

Index: include/gpu/GrGpuResource.h
diff --git a/include/gpu/GrGpuResource.h b/include/gpu/GrGpuResource.h
index f20bad3e9f57580ba416711a337bac071aada82c..61849e7232fd9f23df1219429d7355580a2606ef 100644
--- a/include/gpu/GrGpuResource.h
+++ b/include/gpu/GrGpuResource.h
@@ -80,9 +80,14 @@ public:
 #endif
     }
 
+
 protected:
     GrIORef() : fRefCnt(1), fPendingReads(0), fPendingWrites(0) {}
 
+    bool internalHasPendingRead() const { return SkToBool(fPendingReads); }
+    bool internalHasPendingWrite() const { return SkToBool(fPendingWrites); }
+    bool internalHasPendingIO() const { return SkToBool(fPendingWrites | fPendingReads); }
+
 private:
     void addPendingRead() const {
         this->validate();