Enabling page visibility api in the chrome browser.

chrome/browser/ui/browser.cc

 // Copyright (c) 2011 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/ui/browser.h"
 
 #if defined(OS_WIN)
 #include <shellapi.h>
 #include <windows.h>
 #endif  // OS_WIN
@@ skipping 3346 matching lines @@
 }
 
 void Browser::WorkerCrashed() {
   TabContents* tab_contents = GetSelectedTabContents();
   if (!tab_contents)
     return;
   tab_contents->AddInfoBar(new SimpleAlertInfoBarDelegate(tab_contents, NULL,
       l10n_util::GetStringUTF16(IDS_WEBWORKER_CRASHED_PROMPT), true));
 }
 
+bool Browser::IsHidden(const TabContents* source) const {
+  TabContentsWrapper* wrapper = GetSelectedTabContentsWrapper();
+  if (wrapper)
+    return wrapper->tab_contents() != source;
+  // If we cant find the tab contents, assume we are not visible.
+  return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Browser, TabContentsWrapperDelegate implementation:
 
 void Browser::OnDidGetApplicationInfo(TabContentsWrapper* source,
                                       int32 page_id) {
   if (GetSelectedTabContentsWrapper() != source)
     return;
 
   NavigationEntry* entry = source->controller().GetLastCommittedEntry();
   if (!entry || (entry->page_id() != page_id))
@@ skipping 1237 matching lines @@
   TabContents* current_tab = GetSelectedTabContents();
   if (current_tab) {
     content_restrictions = current_tab->content_restrictions();
     NavigationEntry* active_entry = current_tab->controller().GetActiveEntry();
     // See comment in UpdateCommandsForTabState about why we call url().
     if (!SavePackage::IsSavableURL(active_entry ? active_entry->url() : GURL()))
       content_restrictions |= CONTENT_RESTRICTION_SAVE;
   }
   return content_restrictions;
 }