Extracts CT DNS test utilities into a standalone class

components/certificate_transparency/BUILD.gn

Index: components/certificate_transparency/BUILD.gn
diff --git a/components/certificate_transparency/BUILD.gn b/components/certificate_transparency/BUILD.gn
index 3bba1a1405953818a2344e43133f7f9fcfe994fc..17a27ebe9fba463d27c768e872ace5fe43dc4099 100644
--- a/components/certificate_transparency/BUILD.gn
+++ b/components/certificate_transparency/BUILD.gn
@@ -30,6 +30,23 @@ source_set("certificate_transparency") {
   ]
 }
 
+source_set("test_support") {

[Eran Messeri, 2016/07/21 14:47:02]

I suggest adding the mock_log_dns_traffic files to the unit_tests source_set and
not introducing another build rule until something outside of
components/certificate_transparency needs it.

[Rob Percival, 2016/07/21 15:27:19]

Done.

+  testonly = true
+  sources = [
+    "mock_log_dns_traffic.cc",
+    "mock_log_dns_traffic.h",
+  ]
+  public_deps = [
+    ":certificate_transparency",
+  ]
+  deps = [
+    "//base",
+    "//net",
+    "//net:test_support",
+    "//testing/gtest",
+  ]
+}
+
 source_set("unit_tests") {
   testonly = true
   sources = [
@@ -38,9 +55,8 @@ source_set("unit_tests") {
     "log_proof_fetcher_unittest.cc",
     "single_tree_tracker_unittest.cc",
   ]
-
   deps = [
-    ":certificate_transparency",
+    ":test_support",
     "//base/test:test_support",
     "//components/prefs:test_support",
     "//components/safe_json:test_support",