Add flag on GrBackendTexture to say whether texture is mipped or not

Bug: skia:
Change-Id: Ia684e3daf779ec2feaaec64c04dabf5cb03cd07a
Reviewed-on: https://skia-review.googlesource.com/57821
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
diff --git a/gn/tests.gni b/gn/tests.gni
index a6135ed..3c42b80 100644
--- a/gn/tests.gni
+++ b/gn/tests.gni
@@ -92,6 +92,7 @@
   "$_tests/GrContextFactoryTest.cpp",
   "$_tests/GrMemoryPoolTest.cpp",
   "$_tests/GrMeshTest.cpp",
+  "$_tests/GrMipMappedTest.cpp",
   "$_tests/GrPipelineDynamicStateTest.cpp",
   "$_tests/GrPorterDuffTest.cpp",
   "$_tests/GrShapeTest.cpp",