Cache render targets that render to wrapped textures

src/gpu/GrTextureProvider.cpp

Index: src/gpu/GrTextureProvider.cpp
diff --git a/src/gpu/GrTextureProvider.cpp b/src/gpu/GrTextureProvider.cpp
index 3596ba6c12ce3287deb489a6d760d1344d4abc9b..ee4f651c1078558d3a8cfe42910d6249afa02fc1 100644
--- a/src/gpu/GrTextureProvider.cpp
+++ b/src/gpu/GrTextureProvider.cpp
@@ -199,3 +199,14 @@ GrTexture* GrTextureProvider::findAndRefTextureByUniqueKey(const GrUniqueKey& ke
     }
     return NULL;
 }
+
+GrRenderTarget* GrTextureProvider::findAndRefRenderTargetByUniqueKey(const GrUniqueKey& key) {
+    ASSERT_SINGLE_OWNER
+    GrGpuResource* resource = this->findAndRefResourceByUniqueKey(key);
+    if (resource) {
+        GrRenderTarget* rt = static_cast<GrSurface*>(resource)->asRenderTarget();
+        SkASSERT(rt);
+        return rt;
+    }
+    return nullptr;
+}