While screencasting a tab, do not disable rendering updates while hidden.

content/browser/web_contents/web_contents_impl.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 766 matching lines @@
   std::string contents_mime_type_;
 
   // Character encoding.
   std::string encoding_;
 
   // True if this is a secure page which displayed insecure content.
   bool displayed_insecure_content_;
 
   // Data for misc internal state ----------------------------------------------
 
-  // Whether the WebContents is currently being screenshotted.
-  bool capturing_contents_;
+  // When > 0, the WebContents is currently being captured (e.g., for
+  // screenshots or mirroring); and the underlying RenderWidgetHost should not
+  // be told it is hidden.
+  int capturing_count_;
 
   // See getter above.
   bool is_being_destroyed_;
 
   // Indicates whether we should notify about disconnection of this
   // WebContentsImpl. This is used to ensure disconnection notifications only
   // happen if a connection notification has happened and that they happen only
   // once.
   bool notify_disconnection_;
 
@@ skipping 77 matching lines @@
   // Maps the ids of pending favicon downloads to their callbacks
   typedef std::map<int, FaviconDownloadCallback> FaviconDownloadMap;
   FaviconDownloadMap favicon_download_map_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_