Use a struct for client GL texture handles

tests/GrSurfaceTest.cpp

Index: tests/GrSurfaceTest.cpp
diff --git a/tests/GrSurfaceTest.cpp b/tests/GrSurfaceTest.cpp
index 24ffc7c5d311390a26dbad8ce1114090e713a54a..bc24d1c02a87a33e64b8d98d0813e5a32b6ea107 100644
--- a/tests/GrSurfaceTest.cpp
+++ b/tests/GrSurfaceTest.cpp
@@ -11,6 +11,7 @@
 
 #include "GrContext.h"
 #include "GrContextFactory.h"
+#include "GrGpu.h"
 #include "GrRenderTarget.h"
 #include "GrTexture.h"
 #include "GrSurfacePriv.h"
@@ -44,13 +45,16 @@ DEF_GPUTEST(GrSurface, reporter, factory) {
         REPORTER_ASSERT(reporter, tex1 == tex1->asTexture());
         REPORTER_ASSERT(reporter, static_cast<GrSurface*>(tex1) == tex1->asTexture());
 
+        GrBackendObject backendTex = context->getGpu()->createTestingOnlyBackendTexture(
+            nullptr, 256, 256, kSkia8888_GrPixelConfig);
+
         GrBackendTextureDesc backendDesc;
         backendDesc.fConfig = kSkia8888_GrPixelConfig;
         backendDesc.fFlags = kRenderTarget_GrBackendTextureFlag;
         backendDesc.fWidth = 256;
         backendDesc.fHeight = 256;
         backendDesc.fSampleCnt = 0;
-        backendDesc.fTextureHandle = 5;
+        backendDesc.fTextureHandle = backendTex;
         GrSurface* texRT2 = context->textureProvider()->wrapBackendTexture(
             backendDesc, kBorrow_GrWrapOwnership);
         REPORTER_ASSERT(reporter, texRT2 == texRT2->asRenderTarget());
@@ -60,11 +64,12 @@ DEF_GPUTEST(GrSurface, reporter, factory) {
         REPORTER_ASSERT(reporter, texRT2->asRenderTarget() ==
                                   static_cast<GrSurface*>(texRT2->asTexture()));
         REPORTER_ASSERT(reporter, static_cast<GrSurface*>(texRT2->asRenderTarget()) ==
-                                   static_cast<GrSurface*>(texRT2->asTexture()));
+                                  static_cast<GrSurface*>(texRT2->asTexture()));
 
         texRT1->unref();
         texRT2->unref();
         tex1->unref();
+        context->getGpu()->deleteTestingOnlyBackendTexture(backendTex);
     }
 }