Expose the visibility state of a frame to the browser process.

chrome/browser/chrome_content_browser_client.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 CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 #define CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_
 
 #include <set>
 #include <string>
 #include <utility>
@@ skipping 239 matching lines @@
       ScopedVector<storage::FileSystemBackend>* additional_backends) override;
   content::DevToolsManagerDelegate* GetDevToolsManagerDelegate() override;
   bool IsPluginAllowedToCallRequestOSFileHandle(
       content::BrowserContext* browser_context,
       const GURL& url) override;
   bool IsPluginAllowedToUseDevChannelAPIs(
       content::BrowserContext* browser_context,
       const GURL& url) override;
   net::CookieStore* OverrideCookieStoreForRenderProcess(
       int render_process_id) override;
+  void OverridePageVisibilityState(
+      content::RenderFrameHost* render_frame_host,
+      blink::WebPageVisibilityState* visibility_state) override;
 
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
   void GetAdditionalMappedFilesForChildProcess(
       const base::CommandLine& command_line,
       int child_process_id,
       content::FileDescriptorInfo* mappings) override;
 #endif
 #if defined(OS_WIN)
   virtual const wchar_t* GetResourceDllName() override;
   virtual void PreSpawnRenderer(sandbox::TargetPolicy* policy,
@@ skipping 58 matching lines @@
   std::vector<ChromeContentBrowserClientParts*> extra_parts_;
 
   base::WeakPtrFactory<ChromeContentBrowserClient> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeContentBrowserClient);
 };
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_CHROME_CONTENT_BROWSER_CLIENT_H_