Fix web_accesible_resources enforcement for Site Isolation.

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index c279e1a2163b629b07dd3f3f503df06109cc352d..81eecf7df019692bdc831ba474cdee6412e8084d 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -268,6 +268,7 @@
 #include "chrome/browser/speech/extension_api/tts_engine_extension_api.h"
 #include "components/guest_view/browser/guest_view_base.h"
 #include "components/guest_view/browser/guest_view_manager.h"
+#include "extensions/browser/extension_navigation_throttle.h"
 #include "extensions/browser/extension_registry.h"
 #include "extensions/browser/extension_util.h"
 #include "extensions/browser/guest_view/web_view/web_view_guest.h"
@@ -2923,6 +2924,11 @@ ChromeContentBrowserClient::CreateThrottlesForNavigation(
   }
 #endif
 
+#if defined(ENABLE_EXTENSIONS)
+  if (!handle->IsInMainFrame())
+    throttles.push_back(new extensions::ExtensionNavigationThrottle(handle));
+#endif
+
   return throttles;
 }