Work on "gn check" of content/*

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
index 37ccf23f4073ce7d67a294a8dbff2dc5b507109d..021f08a20b94f103ebc40a5c0445f91e6de0aa29 100644
--- a/content/public/renderer/BUILD.gn
+++ b/content/public/renderer/BUILD.gn
@@ -14,14 +14,22 @@ source_set("renderer") {
   ]
 
   deps = [
+    "//content/public/common",
     "//content/renderer",
     "//skia",
     "//third_party/libjingle",
     "//third_party/WebKit/public:blink_headers",
     "//third_party/widevine/cdm:version_h",
+    "//ui/gfx",
     "//v8",
   ]
 
+  allow_circular_includes_from = [
+    # This target is a pair with content/renderer. They always go together and
+    # include headers from each other.
+    "//content/renderer",
+  ]
+
   if (enable_webrtc) {
     sources += rebase_path(
         content_renderer_gypi_values.public_renderer_webrtc_sources,