GN: Build rules and fixes for (almost) all mojo unittest targets

mojo/public/cpp/test_support/BUILD.gn

Index: mojo/public/cpp/test_support/BUILD.gn
diff --git a/components/auto_login_parser/BUILD.gn b/mojo/public/cpp/test_support/BUILD.gn
similarity index 50%
copy from components/auto_login_parser/BUILD.gn
copy to mojo/public/cpp/test_support/BUILD.gn
index af92f0fa5483d43264361ea87dbaf59e2f9ac945..9599161158f0241f307fa9f31d0c982d2668e574 100644
--- a/components/auto_login_parser/BUILD.gn
+++ b/mojo/public/cpp/test_support/BUILD.gn
@@ -2,25 +2,17 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("auto_login_parser") {
-  sources = [
-    "auto_login_parser.cc",
-    "auto_login_parser.h",
-  ]
-
+# GYP version: mojo/mojo_public_tests.gypi:mojo_public_test_utils
+source_set("test_utils") {
   deps = [
     "//base",
-    "//net",
+    "//testing/gtest",
+    "//mojo/public/c/test_support",
   ]
-}
 
-source_set("unit_tests") {
   sources = [
-    "auto_login_parser_unittest.cc",
-  ]
-
-  deps = [
-    ":auto_login_parser",
-    "//testing/gtest",
+    "lib/test_support.cc",
+    "lib/test_utils.cc",
+    "test_utils.h",
   ]
 }