Backdoor to get the number of texture lazy clears for testing

Bug: dawn:145
Change-Id: Ie01b21ce490832c459e74c76a7b8d9f203552bfe
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/9400
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: Natasha Lee <natlee@microsoft.com>

src/dawn_native/opengl/TextureGL.cpp

@@ -222,6 +222,7 @@ namespace dawn_native { namespace opengl {
             }
         }
         SetIsSubresourceContentInitialized(baseMipLevel, levelCount, baseArrayLayer, layerCount);
+        GetDevice()->IncrementLazyClearCountForTesting();
     }
 
     void Texture::EnsureSubresourceContentInitialized(uint32_t baseMipLevel,