Add GN isolate support for a bunch of unittests.

This enables the following tests to be run under
swarming on a GN bot:

- angle_unittests
- accessibility_unittests
- compositor_unittests
- cc_unittests
- ipc_tests
- gl_unittests
- sandbox_linux_unittests
- gn_unittests
- skia_unittests
- sql_unittests
- url_unittests

R=brettw@chromium.org, maruel@chromium.org
BUG=504079
CQ_EXTRA_TRYBOTS=tryserver.chromium.mac:mac_chromium_gn_rel

Review URL: https://codereview.chromium.org/1248673005

Cr-Original-Commit-Position: refs/heads/master@{#339973}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 177c1e29c1abeb267b3ab1283a4c7c03a398ec6f
diff --git a/tools/gn/BUILD.gn b/tools/gn/BUILD.gn
index 3109f75..39fee93 100644
--- a/tools/gn/BUILD.gn
+++ b/tools/gn/BUILD.gn
@@ -226,6 +226,15 @@
   ]
 }
 
+# TODO(GYP): Delete this after we've converted everything to GN.
+# The _run targets exist only for compatibility w/ GYP.
+group("gn_unittests_run") {
+  testonly = true
+  deps = [
+    ":gn_unittests",
+  ]
+}
+
 test("gn_unittests") {
   sources = [
     "action_target_generator_unittest.cc",
@@ -281,6 +290,11 @@
     "value_unittest.cc",
     "visibility_unittest.cc",
   ]
+
+  data = [
+    "format_test_data/",
+  ]
+
   deps = [
     ":gn_lib",
     "//base/test:run_all_unittests",