[android_webview] Enable navigation interception for iframes.

content/components/navigation_interception/intercept_navigation_resource_throttle.cc

Index: content/components/navigation_interception/intercept_navigation_resource_throttle.cc
diff --git a/content/components/navigation_interception/intercept_navigation_resource_throttle.cc b/content/components/navigation_interception/intercept_navigation_resource_throttle.cc
index 894fb0c1a98f20dd74e37f96891f92496961f611..68a67e2c713f9ff370b80689e287fabb4c3fbf68 100644
--- a/content/components/navigation_interception/intercept_navigation_resource_throttle.cc
+++ b/content/components/navigation_interception/intercept_navigation_resource_throttle.cc
@@ -94,9 +94,6 @@ bool InterceptNavigationResourceThrottle::CheckIfShouldIgnoreNavigation(
   if (!info->GetAssociatedRenderView(&render_process_id, &render_view_id))
     return false;
 
-  // This class should only be instantiated for top level frame requests.
-  DCHECK(info->IsMainFrame());
-
   ShouldIgnoreCallbackParams params;
   params.render_process_id = render_process_id;
   params.render_view_id = render_view_id;