Give the main frame a RenderWidget.

chrome/browser/extensions/api/tab_capture/offscreen_tab.cc

 // Copyright 2015 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 "chrome/browser/extensions/api/tab_capture/offscreen_tab.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "chrome/browser/extensions/api/tab_capture/tab_capture_registry.h"
@@ skipping 270 matching lines @@
     const content::DropData& data,
     blink::WebDragOperationsMask operations_allowed) {
   DCHECK_EQ(offscreen_tab_web_contents_.get(), source);
   // Halt all drag attempts onto the page since there should be no direct user
   // interaction with it.
   return false;
 }
 
 bool OffscreenTab::ShouldCreateWebContents(
     WebContents* contents,
-    int route_id,
-    int main_frame_route_id,
+    int32_t route_id,
+    int32_t main_frame_route_id,
+    int32_t main_frame_widget_route_id,
     WindowContainerType window_container_type,
     const std::string& frame_name,
     const GURL& target_url,
     const std::string& partition_id,
     content::SessionStorageNamespace* session_storage_namespace) {
   DCHECK_EQ(offscreen_tab_web_contents_.get(), contents);
   // Disallow creating separate WebContentses.  The WebContents implementation
   // uses this to spawn new windows/tabs, which is also not allowed for
   // offscreen tabs.
   return false;
@@ skipping 141 matching lines @@
 
   // Schedule the timer to check again in a second.
   capture_poll_timer_.Start(
       FROM_HERE,
       base::TimeDelta::FromSeconds(kPollIntervalInSeconds),
       base::Bind(&OffscreenTab::DieIfContentCaptureEnded,
                  base::Unretained(this)));
 }
 
 }  // namespace extensions