Fix web_accesible_resources enforcement for Site Isolation.

extensions/browser/extension_navigation_throttle.h

Index: extensions/browser/extension_navigation_throttle.h
diff --git a/extensions/browser/extension_navigation_throttle.h b/extensions/browser/extension_navigation_throttle.h
new file mode 100644
index 0000000000000000000000000000000000000000..354269387e34fba865f0df7bcab44b10dc524f85
--- /dev/null
+++ b/extensions/browser/extension_navigation_throttle.h
@@ -0,0 +1,36 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef EXTENSIONS_BROWSER_EXTENSION_NAVIGATION_THROTTLE_H_
+#define EXTENSIONS_BROWSER_EXTENSION_NAVIGATION_THROTTLE_H_
+
+#include "base/macros.h"
+#include "content/public/browser/navigation_throttle.h"
+
+namespace content {
+class NavigationHandle;
+}
+
+namespace extensions {
+
+class NavigationParams;
+
+// This class allows the extensions subsystem to have control over navigations
+// and optionally cancel/block them. This is a UI thread class.
+class ExtensionNavigationThrottle : public content::NavigationThrottle {
+ public:
+  explicit ExtensionNavigationThrottle(
+      content::NavigationHandle* navigation_handle);
+  ~ExtensionNavigationThrottle() override;
+
+  // content::NavigationThrottle implementation:
+  ThrottleCheckResult WillStartRequest() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ExtensionNavigationThrottle);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_EXTENSION_NAVIGATION_THROTTLE_H_