Temporary patch for Mus/Viz

Change-Id: I2936be1d5d0d4b65a9d04b6b9c8bf95b3644dad8
Reviewed-on: https://skia-review.googlesource.com/113714
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>

src/gpu/GrTextureAdjuster.cpp

@@ -75,7 +75,12 @@ sk_sp<GrTextureProxy> GrTextureAdjuster::refTextureProxySafeForParams(const GrSa
         return nullptr;
     }
 
+    // DDL TODO: remove the need for the GrGpu in this method
     GrGpu* gpu = fContext->contextPriv().getGpu();
+    if (!gpu) {
+        return proxy;
+    }
+
     if (!gpu->isACopyNeededForTextureParams(proxy.get(), params, &copyParams, scaleAdjust)) {
         return proxy;
     }