gc: Add library and test targets

Adds a target for the library and test targets.

- Integrate into compontents_unittests as all other components do as
  well. This ensures that unittests are automatically run on CI.
- Provide a separate gc_unittests binary as the components binary
  requires ~35k files to build.

Bug: 1056170
Change-Id: I8fa235c239f2dc5217145c12abb8c1f27af84fc5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2080422
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745597}

BUILD.gn

@@ -73,6 +73,7 @@ group("gn_all") {
     "//chrome/installer",
     "//chrome/updater",
     "//components:components_unittests",
+    "//components/gc:gc_unittests",
     "//components/gwp_asan:gwp_asan_unittests",
     "//net:net_unittests",
     "//services:services_unittests",

components/BUILD.gn

@@ -36,9 +36,7 @@ if (is_ios) {
       "$root_out_dir/components_tests_resources.pak",
       "$root_out_dir/ui_test.pak",
     ]
-    outputs = [
-      "{{bundle_resources_dir}}/{{source_file_part}}",
-    ]
+    outputs = [ "{{bundle_resources_dir}}/{{source_file_part}}" ]
   }
 }
 
@@ -48,9 +46,7 @@ if (is_ios) {
 # test target if convenient.
 test("components_unittests") {
   if (is_android || is_linux || is_mac || is_win) {
-    data = [
-      "test/data/",
-    ]
+    data = [ "test/data/" ]
   }
 
   # Add only ":unit_tests" dependencies here. If your tests have dependencies
@@ -93,6 +89,7 @@ test("components_unittests") {
     "//components/filename_generation:unit_tests",
     "//components/flags_ui:unit_tests",
     "//components/games/core:unit_tests",
+    "//components/gc:unit_tests",
     "//components/gcm_driver:unit_tests",
     "//components/gcm_driver/crypto:unit_tests",
     "//components/google/core/common:unit_tests",

components/gc/BUILD.gn

+# Copyright 2020 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import("//testing/test.gni")
+
+component("gc") {
+  sources = [
+    "core/gc.cc",
+    "core/gc_export.h",
+  ]
+
+  deps = []
+
+  defines = [ "GC_IMPLEMENTATION=1" ]
+}
+
+source_set("unit_tests") {
+  testonly = true
+
+  sources = []
+
+  deps = [
+    ":gc",
+    "//testing/gtest",
+  ]
+}
+
+# Convenience target to allow just building GC-related tests for local development.
+test("gc_unittests") {
+  testonly = true
+
+  sources = [ "test/run_all_unittests.cc" ]
+
+  deps = [
+    ":unit_tests",
+    "//testing/gtest",
+  ]
+}

components/gc/core/gc.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/gc/core/gc_export.h"
+
+namespace gc {
+namespace internal {
+
+GC_EXPORT void Dummy() {
+  // TODO(mlippautz): Placeholder to force building a library. Remove as soon as
+  // actual code is available.
+}
+
+}  // namespace internal
+}  // namespace gc

components/gc/core/gc_export.h

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef COMPONENTS_GC_CORE_GC_EXPORT_H_
+#define COMPONENTS_GC_CORE_GC_EXPORT_H_
+
+#if defined(COMPONENT_BUILD)
+#if defined(WIN32)
+
+#if defined(GC_IMPLEMENTATION)
+#define GC_EXPORT __declspec(dllexport)
+#else
+#define GC_EXPORT __declspec(dllimport)
+#endif  // defined(GC_IMPLEMENTATION)
+
+#else  // defined(WIN32)
+#if defined(GC_IMPLEMENTATION)
+#define GC_EXPORT __attribute__((visibility("default")))
+#else
+#define GC_EXPORT
+#endif  // defined(GC_IMPLEMENTATION)
+#endif
+
+#else  // defined(COMPONENT_BUILD)
+#define GC_EXPORT
+#endif
+
+#endif  // COMPONENTS_GC_CORE_GC_EXPORT_H_

components/gc/test/run_all_unittests.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+int main(int argc, char** argv) {
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}