BUILD.gn: Only build tests in Chromium. (#2392)

The prior GoogleTest integration was incomplete and produced errors
when building with 'gn check' enabled. Fix this by scoping the test
integration to Chromium.

Fixes Issue #2382

BUILD.gn

@@ -657,47 +657,10 @@ group("SPIRV-Tools") {
   ]
 }
 
-if (!build_with_chromium) {
-  googletest_dir = spirv_tools_googletest_dir
-
-  config("gtest_config") {
-    include_dirs = [
-      "${googletest_dir}/googletest",
-      "${googletest_dir}/googletest/include",
-    ]
-  }
-
-  static_library("gtest") {
-    testonly = true
-    sources = [
-      "${googletest_dir}/googletest/src/gtest-all.cc",
-    ]
-    public_configs = [ ":gtest_config" ]
-  }
-
-  config("gmock_config") {
-    include_dirs = [
-      "${googletest_dir}/googlemock",
-      "${googletest_dir}/googlemock/include",
-      "${googletest_dir}/googletest/include",
-    ]
-    if (is_clang) {
-      # TODO: Can remove this if/when the issue is fixed.
-      # https://github.com/google/googletest/issues/533
-      cflags = [ "-Wno-inconsistent-missing-override" ]
-    }
-  }
-
-  static_library("gmock") {
-    testonly = true
-    sources = [
-      "${googletest_dir}/googlemock/src/gmock-all.cc",
-    ]
-    public_configs = [ ":gmock_config" ]
-  }
-}
-
-test("spvtools_test") {
+# The tests are scoped to Chromium to avoid needing to write gtest integration.
+# See Chromium's third_party/googletest/BUILD.gn for a complete integration.
+if (build_with_chromium) {
+  test("spvtools_test") {
     sources = [
       "test/assembly_context_test.cpp",
       "test/assembly_format_test.cpp",
@@ -759,30 +722,20 @@ test("spvtools_test") {
     ]
 
     deps = [
+      "//testing/gmock",
+      "//testing/gtest",
+      "//testing/gtest:gtest_main",
       ":spvtools",
       ":spvtools_language_header_unified1",
       ":spvtools_val",
     ]
 
-  if (build_with_chromium) {
-    deps += [
-      "//testing/gmock",
-      "//testing/gtest",
-      "//testing/gtest:gtest_main",
-    ]
-  } else {
-    deps += [
-      ":gmock",
-      ":gtest",
-    ]
-    sources += [ "${googletest_dir}/googletest/src/gtest_main.cc" ]
-  }
-
     if (is_clang) {
       cflags_cc = [ "-Wno-self-assign" ]
     }
 
     configs += [ ":spvtools_internal_config" ]
+  }
 }
 
 if (spirv_tools_standalone) {