Fix DisownOpener and related tests.

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 <utility>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 3652 matching lines @@
   // to let the user edit it and try again.  Clear it now that content might
   // show up underneath it.
   if (!IsLoading() && controller_.GetPendingEntry())
     controller_.DiscardPendingEntry();
 
   // Update the URL display.
   NotifyNavigationStateChanged(content::INVALIDATE_TYPE_URL);
 }
 
 void WebContentsImpl::DidDisownOpener(RenderFrameHost* render_frame_host) {
-  if (opener_) {
-    // Clear our opener so that future cross-process navigations don't have an
-    // opener assigned.
-    RemoveDestructionObserver(opener_);
-    opener_ = NULL;
-  }
+  // No action is necessary if the opener has already been cleared.

[Charlie Reis, 2014/08/22 19:41:23]

Bug 4: There was a risk of sending unnecessary notifications if the opener had
already been cleared.

+  if (!opener_)
+    return;
+
+  // Clear our opener so that future cross-process navigations don't have an
+  // opener assigned.
+  RemoveDestructionObserver(opener_);
+  opener_ = NULL;
 
   // Notify all swapped out RenderViewHosts for this tab.  This is important
   // in case we go back to them, or if another window in those processes tries
   // to access window.opener.
   GetRenderManager()->DidDisownOpener(render_frame_host->GetRenderViewHost());
 }
 
 void WebContentsImpl::DocumentOnLoadCompleted(
     RenderFrameHost* render_frame_host) {
   FOR_EACH_OBSERVER(WebContentsObserver, observers_,
@@ skipping 551 matching lines @@
   node->render_manager()->ResumeResponseDeferredAtStart();
 }
 
 void WebContentsImpl::SetForceDisableOverscrollContent(bool force_disable) {
   force_disable_overscroll_content_ = force_disable;
   if (view_)
     view_->SetOverscrollControllerEnabled(CanOverscrollContent());
 }
 
 }  // namespace content