Add more components unittests to the GN build.

components/captive_portal/BUILD.gn

Index: components/captive_portal/BUILD.gn
diff --git a/components/captive_portal/BUILD.gn b/components/captive_portal/BUILD.gn
index e0a07b62307a3933a49cdc72762389a3eaf26cc4..3bf2fccb545ac6cca825d91f17263502ef533083 100644
--- a/components/captive_portal/BUILD.gn
+++ b/components/captive_portal/BUILD.gn
@@ -20,7 +20,7 @@ component("captive_portal") {
   ]
 }
 
-static_library("test_support") {
+source_set("test_support") {
   testonly = true
   sources = [
     "captive_portal_testing_utils.cc",
@@ -30,7 +30,7 @@ static_library("test_support") {
   deps = [
     ":captive_portal",
     "//base",
-    "//net",
+    "//net:test_support",
     "//url",
   ]
 }
@@ -43,6 +43,9 @@ source_set("unit_tests") {
 
   deps = [
     ":captive_portal",
+    ":test_support",
+    "//base",
+    "//net:test_support",
     "//testing/gtest",
   ]
 }