[TooManyTabs] Add TabNavigationThrottle

content/browser/web_contents/web_contents_impl.cc

 // 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.
 
 #include "content/browser/web_contents/web_contents_impl.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <utility>
@@ skipping 1487 matching lines @@
   }
 
   last_hidden_time_ = base::TimeTicks::Now();
 
   for (auto& observer : observers_)
     observer.WasHidden();
 
   should_normally_be_visible_ = false;
 }
 
+bool WebContentsImpl::IsVisible() const {
+  return should_normally_be_visible_;
+}
+
 void WebContentsImpl::WasOccluded() {
   if (capturer_count_ > 0)
     return;
 
   for (RenderWidgetHostView* view : GetRenderWidgetHostViewsInTree())
     view->WasOccluded();
 }
 
 void WebContentsImpl::WasUnOccluded() {
   for (RenderWidgetHostView* view : GetRenderWidgetHostViewsInTree())
@@ skipping 4202 matching lines @@
     new_root->SetOriginalOpener(opener->frame_tree()->root());
 
     if (!opener_suppressed) {
       new_root->SetOpener(opener);
       created_with_opener_ = true;
     }
   }
 }
 
 }  // namespace content