Add custom interstitial for captive portals.

chrome/browser/captive_portal/captive_portal_service.h

Index: chrome/browser/captive_portal/captive_portal_service.h
diff --git a/chrome/browser/captive_portal/captive_portal_service.h b/chrome/browser/captive_portal/captive_portal_service.h
index 66e6d1b4182049e14af547361a2e04522fe8148f..5a93b84ac05d2f862d86c31beaf91aba7d8cd4b3 100644
--- a/chrome/browser/captive_portal/captive_portal_service.h
+++ b/chrome/browser/captive_portal/captive_portal_service.h
@@ -50,6 +50,9 @@ class CaptivePortalService : public KeyedService, public base::NonThreadSafe {
   // Always sends the result notification asynchronously.
   void DetectCaptivePortal();
 
+  // Enables or disables actual portal checks.
+  void SetPortalDetectionEnabledForTest(bool enabled);
+
   // Returns the URL used for captive portal testing.  When a captive portal is
   // detected, this URL will take us to the captive portal landing page.
   const GURL& test_url() const { return test_url_; }
@@ -204,6 +207,9 @@ class CaptivePortalService : public KeyedService, public base::NonThreadSafe {
   // Test time ticks used by unit tests.
   base::TimeTicks time_ticks_for_testing_;
 
+  // If true, portal detection is enabled. Only false in tests.
+  bool portal_detection_enabled_;
+
   DISALLOW_COPY_AND_ASSIGN(CaptivePortalService);
 };