Add an even more convenient way to declare tests, with example.

tests/AAClipTest.cpp

Index: tests/AAClipTest.cpp
diff --git a/tests/AAClipTest.cpp b/tests/AAClipTest.cpp
index e3be006e575db727b0d8668b29d7f309f7be3ceb..f70cfd679ff669fe0fb9924fc79b4d63192e7ae3 100644
--- a/tests/AAClipTest.cpp
+++ b/tests/AAClipTest.cpp
@@ -394,7 +394,8 @@ static void test_regressions() {
     }
 }
 
-static void TestAAClip(skiatest::Reporter* reporter) {
+#include "TestClassDef.h"
+DEF_TEST(AAClip, reporter) {
     test_empty(reporter);
     test_path_bounds(reporter);
     test_irect(reporter);
@@ -403,6 +404,3 @@ static void TestAAClip(skiatest::Reporter* reporter) {
     test_regressions();
     test_nearly_integral(reporter);
 }
-
-#include "TestClassDef.h"
-DEFINE_TESTCLASS("AAClip", AAClipTestClass, TestAAClip)