Android: Add skia_unittests to the list of stable test suites.

That way the android trybots and cq will be able to run it.

It should fix the following error:
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_dbg_tests_recipe/builds/44344/steps/skia_unittests/logs/stdio

Traceback (most recent call last):
          File
          "/b/build/slave/android/build/src/build/android/test_runner.py",
          line 990, in <module>
              sys.exit(main())
            File
          "/b/build/slave/android/build/src/build/android/test_runner.py",
          line 986, in main
              return RunTestsCommand(args, parser)
            File
          "/b/build/slave/android/build/src/build/android/test_runner.py",
          line 880, in RunTestsCommand
              return _RunGTests(args, devices)
            File
          "/b/build/slave/android/build/src/build/android/test_runner.py",
          line 617, in _RunGTests
              runner_factory, tests = gtest_setup.Setup(gtest_options,
                              devices)
            File
          "/b/build/slave/android/build/src/build/android/pylib/gtest/setup.py",
          line 218, in Setup
              tests = _GetTests(test_options, test_package, devices)
            File
          "/b/build/slave/android/build/src/build/android/pylib/gtest/setup.py",
          line 128, in _GetTests
              tests.extend(r.test_list)
          AttributeError: 'BaseTestResult' object has no attribute
                           'test_list

BUG=444058
R=jbudorick@chromium.org

Review URL: https://codereview.chromium.org/849623004

Cr-Commit-Position: refs/heads/master@{#311197}

build/android/pylib/gtest/gtest_config.py

@@ -33,6 +33,7 @@
     'media_unittests',
     'net_unittests',
     'sandbox_linux_unittests',
+    'skia_unittests',
     'sql_unittests',
     'sync_unit_tests',
     'ui_android_unittests',

skia/skia_tests.gyp

@@ -42,6 +42,11 @@
             'ext/platform_canvas_unittest.cc',
           ],
         }],
+        ['OS == "android"', {
+          'dependencies': [
+            '../testing/android/native_test.gyp:native_test_native_code',
+          ],
+        }],
       ],
     },
   ],