Revert of Don't refer browser-initiated navigations to web-safe URLs to delegate.

extensions/browser/guest_view/web_view/web_view_guest.cc

 // Copyright 2014 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.
 
 #include "extensions/browser/guest_view/web_view/web_view_guest.h"
 
 #include "base/message_loop/message_loop.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/browsing_data/storage_partition_http_cache_data_remover.h"
@@ skipping 1195 matching lines @@
     *was_blocked = false;
   RequestNewWindowPermission(disposition,
                              initial_rect,
                              user_gesture,
                              new_contents);
 }
 
 content::WebContents* WebViewGuest::OpenURLFromTab(
     content::WebContents* source,
     const content::OpenURLParams& params) {
-  // Most navigations should be handled by WebViewGuest::LoadURLWithParams,
-  // which takes care of blocking chrome:// URLs and other web-unsafe schemes.
-  // (NavigateGuest and CreateNewGuestWebViewWindow also go through
-  // LoadURLWithParams.)
-  //
-  // We make an exception here for context menu items, since the Language
-  // Settings item uses a browser-initiated navigation to a chrome:// URL.
-  // These can be passed to the embedder's WebContentsDelegate so that the
-  // browser performs the action for the <webview>.
-  if (!params.is_renderer_initiated &&
-      !content::ChildProcessSecurityPolicy::GetInstance()->IsWebSafeScheme(
-          params.url.scheme())) {
+  // There are two use cases to consider from a security perspective:
+  // 1.) Renderer-initiated navigation to chrome:// must always be blocked even
+  //     if the <webview> is in WebUI. This is handled by
+  //     WebViewGuest::LoadURLWithParams. WebViewGuest::NavigateGuest will also
+  //     call LoadURLWithParams. CreateNewGuestWebViewWindow creates a new
+  //     WebViewGuest which will call NavigateGuest in DidInitialize.
+  // 2.) The Language Settings context menu item should always work, both in
+  //     Chrome Apps and WebUI. This is a browser initiated request and so
+  //     we pass it along to the embedder's WebContentsDelegate to get the
+  //     browser to perform the action for the <webview>.
+  if (!params.is_renderer_initiated) {
     if (!owner_web_contents()->GetDelegate())
       return nullptr;
     return owner_web_contents()->GetDelegate()->OpenURLFromTab(
         owner_web_contents(), params);
   }
 
   // If the guest wishes to navigate away prior to attachment then we save the
   // navigation to perform upon attachment. Navigation initializes a lot of
   // state that assumes an embedder exists, such as RenderWidgetHostViewGuest.
   // Navigation also resumes resource loading which we don't want to allow
@@ skipping 213 matching lines @@
     scoped_ptr<base::DictionaryValue> args(new base::DictionaryValue());
     DispatchEventToView(
         new GuestViewEvent(webview::kEventExitFullscreen, args.Pass()));
   }
   // Since we changed fullscreen state, sending a Resize message ensures that
   // renderer/ sees the change.
   web_contents()->GetRenderViewHost()->WasResized();
 }
 
 }  // namespace extensions