Mark wrapped textures imported into SkImages as "read only".

Read only textures and proxies fail writePixels, as copy dsts, and mip
regeneration.

Bug: skia:8509

Change-Id: Iaa0b473cc9a9930fde3ef0e91373d5040650de35
Reviewed-on: https://skia-review.googlesource.com/c/174316
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 06eb6c4..1b2d13c 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -928,7 +928,8 @@
                                                                  sk_sp<SkColorSpace> colorSpace) {
     ASSERT_SINGLE_OWNER_PRIV
 
-    sk_sp<GrSurfaceProxy> proxy = this->proxyProvider()->wrapBackendTexture(tex, origin);
+    sk_sp<GrSurfaceProxy> proxy = this->proxyProvider()->wrapBackendTexture(
+            tex, origin, kBorrow_GrWrapOwnership, kRW_GrIOType);
     if (!proxy) {
         return nullptr;
     }