Link to further information about cross-origin portal blocking.

And resolve a couple of TODOs.

Bug: 1013389
Change-Id: Iae6b9625dce5ec2319cb2b099678cba11f594e6f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2028251
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Commit-Queue: Lucas Gadani <lfg@chromium.org>
Auto-Submit: Jeremy Roman <jbroman@chromium.org>
Reviewed-by: Lucas Gadani <lfg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736431}

content/browser/portal/portal_navigation_throttle.cc

@@ -17,6 +17,16 @@
 
 namespace content {
 
+namespace {
+
+// A URL where developers can learn more about why this navigation throttle may
+// have cancelled their request.
+const char* GetBlockedInfoURL() {
+  return "https://www.chromium.org/blink/origin-trials/portals";
+}
+
+}  // namespace
+
 // static
 std::unique_ptr<PortalNavigationThrottle>
 PortalNavigationThrottle::MaybeCreateThrottleFor(
@@ -68,13 +78,12 @@ PortalNavigationThrottle::WillStartOrRedirectRequest() {
   if (origin == first_party_origin)
     return PROCEED;
 
-  // TODO(crbug.com/1013389): Update this message to refer to external
-  // documentation if we write any.
   portal->owner_render_frame_host()->AddMessageToConsole(
       blink::mojom::ConsoleMessageLevel::kWarning,
       base::StringPrintf("Navigating a portal to cross-origin content (from "
-                         "%s) is not currently permitted and was blocked.",
-                         origin.Serialize().c_str()));
+                         "%s) is not currently permitted and was blocked. "
+                         "See %s for more information.",
+                         origin.Serialize().c_str(), GetBlockedInfoURL()));
   return CANCEL;
 }
 

content/browser/portal/portal_navigation_throttle.h

@@ -19,9 +19,6 @@ namespace content {
 //
 // This throttle is enabled only when portals are enabled but third-party
 // portals are not, and provides enforcement of that state.
-//
-// Note: This has complicated interactions with portal activation, which are not
-// yet resolved. See https://crbug.com/1013389.
 class CONTENT_EXPORT PortalNavigationThrottle : public NavigationThrottle {
  public:
   static std::unique_ptr<PortalNavigationThrottle> MaybeCreateThrottleFor(