[TooManyTabs] Add TabNavigationThrottle

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 <stdint.h>
 
 #include <functional>
@@ skipping 346 matching lines @@
   base::TerminationStatus GetCrashedStatus() const override;
   int GetCrashedErrorCode() const override;
   bool IsBeingDestroyed() const override;
   void NotifyNavigationStateChanged(InvalidateTypes changed_flags) override;
   void OnAudioStateChanged(bool is_audible) override;
   base::TimeTicks GetLastActiveTime() const override;
   void SetLastActiveTime(base::TimeTicks last_active_time) override;
   base::TimeTicks GetLastHiddenTime() const override;
   void WasShown() override;
   void WasHidden() override;
+  bool IsVisible() const override;
   bool NeedToFireBeforeUnload() override;
   void DispatchBeforeUnload() override;
   void AttachToOuterWebContentsFrame(
       WebContents* outer_web_contents,
       RenderFrameHost* outer_contents_frame) override;
   void DidChangeVisibleSecurityState() override;
   void Stop() override;
   WebContents* Clone() override;
   void ReloadFocusedFrame(bool bypass_cache) override;
   void Undo() override;
@@ skipping 1284 matching lines @@
   // Adds/removes a callback called on creation of each new WebContents.
   static void AddCreatedCallbackForTesting(const CreatedCallback& callback);
   static void RemoveCreatedCallbackForTesting(const CreatedCallback& callback);
 
   DISALLOW_COPY_AND_ASSIGN(FriendWrapper);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_