Cache render targets that render to wrapped textures

src/gpu/GrGpu.h

Index: src/gpu/GrGpu.h
diff --git a/src/gpu/GrGpu.h b/src/gpu/GrGpu.h
index 7a0bb8e6e4796d43f91d7d83df22e9b06efc9d77..db367854099886e2e327120008cb02edff6f1669 100644
--- a/src/gpu/GrGpu.h
+++ b/src/gpu/GrGpu.h
@@ -127,6 +127,10 @@ public:
      */
     GrRenderTarget* wrapBackendRenderTarget(const GrBackendRenderTargetDesc&, GrWrapOwnership);
 
+    void computeBackendTextureKeyForWrapAsRenderTarget(const GrBackendTextureDesc&,
+                                                       GrUniqueKey*);
+    bool rewrapRenderTargetWithBackendTexture(const GrBackendTextureDesc&,
+                                              GrRenderTarget*);
     /**
      * Implements GrTextureProvider::wrapBackendTextureAsRenderTarget
      */
@@ -532,6 +536,11 @@ private:
     virtual GrTexture* onWrapBackendTexture(const GrBackendTextureDesc&, GrWrapOwnership) = 0;
     virtual GrRenderTarget* onWrapBackendRenderTarget(const GrBackendRenderTargetDesc&,
                                                       GrWrapOwnership) = 0;
+
+    virtual void onComputeBackendTextureKeyForWrapAsRenderTarget(const GrBackendTextureDesc&,
+                                                                 GrUniqueKey*) = 0;
+    virtual bool onRewrapRenderTargetWithBackendTexture(const GrBackendTextureDesc&,
+                                                        GrRenderTarget*) = 0;
     virtual GrRenderTarget* onWrapBackendTextureAsRenderTarget(const GrBackendTextureDesc&) = 0;
     virtual GrBuffer* onCreateBuffer(GrBufferType, size_t size, GrAccessPattern) = 0;