Give the main frame a RenderWidget.

chrome/browser/extensions/api/tab_capture/offscreen_presentation.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_TAB_CAPTURE_OFFSCREEN_PRESENTATION_H_
 #define CHROME_BROWSER_EXTENSIONS_API_TAB_CAPTURE_OFFSCREEN_PRESENTATION_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 125 matching lines @@
   bool PreHandleKeyboardEvent(content::WebContents* source,
                               const content::NativeWebKeyboardEvent& event,
                               bool* is_keyboard_shortcut) final;
   bool PreHandleGestureEvent(content::WebContents* source,
                              const blink::WebGestureEvent& event) final;
   bool CanDragEnter(content::WebContents* source,
                     const content::DropData& data,
                     blink::WebDragOperationsMask operations_allowed) final;
   bool ShouldCreateWebContents(
       content::WebContents* contents,
-      int route_id,
-      int main_frame_route_id,
+      int32 route_id,
+      int32 main_frame_route_id,
+      int32 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) final;
   bool EmbedsFullscreenWidget() const final;
   void EnterFullscreenModeForTab(content::WebContents* contents,
                                  const GURL& origin) final;
   void ExitFullscreenModeForTab(content::WebContents* contents) final;
   bool IsFullscreenForTabOrPending(
@@ skipping 53 matching lines @@
   // This is false until after the Start() method is called, and capture of the
   // |presentation_web_contents_| is first detected.
   bool content_capture_was_detected_;
 
   DISALLOW_COPY_AND_ASSIGN(OffscreenPresentation);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_TAB_CAPTURE_OFFSCREEN_PRESENTATION_H_