Fix SkData leaks at GrResourceKey::setCustomData() call sites.

BUG=skia:
TBR=bsalomon@google.com

Review URL: https://codereview.chromium.org/1270103003 .
diff --git a/tests/ResourceCacheTest.cpp b/tests/ResourceCacheTest.cpp
index 571895f..43f0870 100644
--- a/tests/ResourceCacheTest.cpp
+++ b/tests/ResourceCacheTest.cpp
@@ -851,7 +851,8 @@
         make_unique_key<0>(&key2, 0);
         SkAutoTUnref<TestResource> d(SkNEW_ARGS(TestResource, (context->getGpu())));
         int foo = 4132;
-        key2.setCustomData(SkData::NewWithCopy(&foo, sizeof(foo)));
+        SkAutoTUnref<SkData> data(SkData::NewWithCopy(&foo, sizeof(foo)));
+        key2.setCustomData(data.get());
         d->resourcePriv().setUniqueKey(key2);
     }
 
@@ -1242,7 +1243,8 @@
     make_unique_key<0>(&key1, 1);
     make_unique_key<0>(&key2, 2);
     int foo = 4132;
-    key1.setCustomData(SkData::NewWithCopy(&foo, sizeof(foo)));
+    SkAutoTUnref<SkData> data(SkData::NewWithCopy(&foo, sizeof(foo)));
+    key1.setCustomData(data.get());
     REPORTER_ASSERT(reporter, *(int*) key1.getCustomData()->data() == 4132);
     REPORTER_ASSERT(reporter, key2.getCustomData() == nullptr);