Add chrome test support target to GN build.

chrome/renderer/BUILD.gn

 # Copyright 2014 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("//build/config/features.gni")
 import("//tools/grit/grit_rule.gni")
 
 gypi_values = exec_script(
     "//build/gypi_to_gn.py",
     [ rebase_path("../chrome_renderer.gypi") ],
@@ skipping 141 matching lines @@
       # We should isolate the APIs needed by the renderer.
       "//chrome/common/extensions/api",
     ]
   }
 
   # TODO(GYP)
   #       'sources': [
   #         'renderer/printing/print_web_view_helper_pdf_win.cc',
   #       ],
 }
+
+# In GYP this is part of test_support_common.
+source_set("test_support") {
+  testonly = true
+  visibility = [ "//chrome/test:test_support" ]
+
+  sources = [
+    "chrome_mock_render_thread.cc",
+    "chrome_mock_render_thread.h",
+    "safe_browsing/mock_feature_extractor_clock.cc",
+    "safe_browsing/mock_feature_extractor_clock.h",
+    "safe_browsing/test_utils.cc",
+    "safe_browsing/test_utils.h",
+  ]
+
+  deps = [
+    ":renderer",
+    "//content/test:test_support",
+    "//testing/gmock",
+    "//testing/gtest",
+  ]
+
+  if (printing_mode == 1) {
+    deps += [ "//chrome/service" ]
+  }
+  if (printing_mode != 0) {
+    sources += [
+      "printing/mock_printer.cc",
+      "printing/mock_printer.h",
+    ]
+  }
+
+  if (enable_webrtc) {
+    sources += [
+      "media/mock_webrtc_logging_message_filter.cc",
+      "media/mock_webrtc_logging_message_filter.h",
+    ]
+  }
+}