Put back allow_circular_includes_from in GN build.

A previous patch commented these out, but this ended up not being necessary. Put them back.

Review URL: https://codereview.chromium.org/565733003

Cr-Commit-Position: refs/heads/master@{#294460}

content/public/browser/BUILD.gn

@@ -54,8 +54,7 @@ source_set("browser_sources") {
   allow_circular_includes_from = [
     # This target is a pair with content/browser. They always go together and
     # include headers from each other.
-    # TODO(brettw) enable this when this permits non-dependent targets.
-    #"//content/browser",
+    "//content/browser",
   ]
 
   # We expose skia headers in the public API.

content/public/renderer/BUILD.gn

@@ -39,8 +39,7 @@ source_set("renderer_sources") {
   allow_circular_includes_from = [
     # This target is a pair with content/renderer. They always go together and
     # include headers from each other.
-    # TODO(brettw) enable this when this permits non-dependent targets.
-    #"//content/renderer",
+    "//content/renderer",
   ]
 
   if (enable_webrtc) {

content/public/utility/BUILD.gn

@@ -35,8 +35,7 @@ source_set("utility_sources") {
   allow_circular_includes_from = [
     # This target is a pair with content/browser. They always go together and
     # include headers from each other.
-    # TODO(brettw) enable this when this permits non-dependent targets.
-    #"//content/utility",
+    "//content/utility",
   ]
 }