Add content renderer to the GN build

content/public/renderer/BUILD.gn

Index: content/public/renderer/BUILD.gn
diff --git a/content/public/renderer/BUILD.gn b/content/public/renderer/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..f4a51dd1703a8acd155c3d9176af39d1177324ef
--- /dev/null
+++ b/content/public/renderer/BUILD.gn
@@ -0,0 +1,30 @@
+# 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("//content/renderer/renderer.gni")
+
+source_set("renderer") {
+  sources = rebase_path(content_renderer_gypi_values.public_renderer_sources,
+                        ".", "//content")
+
+  configs += [
+    "//content:blink_headers_stub_config",
+    "//content:content_implementation",
+    "//content:libjingle_stub_config",
+    "//content:v8_stub_config",
+    "//content:widevine_stub_config",
+  ]
+
+  deps = [
+    "//content/renderer",
+    "//skia",
+  ]
+
+  if (enable_webrtc) {
+    sources += rebase_path(
+        content_renderer_gypi_values.public_renderer_webrtc_sources,
+        ".", "//content")
+  }
+}