Remove GN GYP generator.

base/test/BUILD.gn

Index: base/test/BUILD.gn
diff --git a/base/test/BUILD.gn b/base/test/BUILD.gn
index ae15fd595966758b1f3f390da2cd1446f1596597..ed100eb26ee6b55881b4d05a5b5911ac8a007110 100644
--- a/base/test/BUILD.gn
+++ b/base/test/BUILD.gn
@@ -5,7 +5,6 @@
 import("//build/config/ui.gni")
 
 static_library("test_support_base") {
-  external = true
   sources = [
     "expectations/expectation.cc",
     "expectations/expectation.h",
@@ -125,7 +124,6 @@ config("perf_test_config") {
 }
 
 static_library("test_support_perf") {
-  external = true
   sources = [
     "run_all_perftests.cc",
   ]
@@ -142,7 +140,6 @@ static_library("test_support_perf") {
 }
 
 static_library("run_all_unittests") {
-  external = true
   sources = [
     "run_all_unittests.cc",
   ]