Set a valid Referrer for ArcExternalProtocolDialog

Constructing a basic default Referrer for ArcExternalProtocolDialog
based on the last committed url.

Bug: None
Test: Build.
Change-Id: I6aeb677d57632198b69c7cc229f92a2571526a0c
Reviewed-on: https://chromium-review.googlesource.com/1072513Reviewed-by: Yusuke Sato <yusukes@chromium.org>
Commit-Queue: David Jacobo <djacobo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561692}

chrome/browser/chromeos/arc/intent_helper/arc_external_protocol_dialog.cc

@@ -25,6 +25,7 @@
 #include "content/public/browser/page_navigator.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/referrer.h"
+#include "third_party/blink/public/platform/web_referrer_policy.h"
 #include "ui/base/page_transition_types.h"
 #include "ui/base/window_open_disposition.h"
 #include "ui/gfx/image/image.h"
@@ -82,9 +83,11 @@ void OpenUrlInChrome(int render_process_host_id,
       ui::PageTransitionFromInt(ui::PAGE_TRANSITION_LINK);
   constexpr bool kIsRendererInitiated = false;
   const content::OpenURLParams params(
-      // TODO(djacobo): Send a non-empty referrer.
-      url, content::Referrer(), WindowOpenDisposition::CURRENT_TAB,
-      page_transition_type, kIsRendererInitiated);
+      url,
+      content::Referrer(web_contents->GetLastCommittedURL(),
+                        blink::kWebReferrerPolicyDefault),
+      WindowOpenDisposition::CURRENT_TAB, page_transition_type,
+      kIsRendererInitiated);
   web_contents->OpenURL(params);
 }