Don't clear controller_ in ExtensionInstalledBubbleView::CloseBubble.

chrome/browser/ui/views/extensions/extension_installed_bubble_view.cc

 // Copyright 2013 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 <algorithm>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/user_metrics_action.h"
@@ skipping 139 matching lines @@
       break;
   }
 
   // Default case.
   if (!reference_view || !reference_view->visible())
     reference_view = browser_view->toolbar()->app_menu_button();
   SetAnchorView(reference_view);
 }
 
 void ExtensionInstalledBubbleView::CloseBubble() {
-  if (controller_ && controller_->anchor_position() ==
+  // This function should only be called once.
+  DCHECK(!GetWidget()->IsClosed());

[Devlin, 2016/10/26 14:34:58]

nit: I'd be more comfortable with this being a release CHECK().  The previous
nulling out of controller and check served to ensure that the below code was
only called once.  Given the sparseness of testing in this area, I don't think a
DCHECK is sufficient to assure us that this method is, in fact, only called
once.

[Evan Stade, 2016/10/26 17:24:22]

Done.

+  if (controller_->anchor_position() ==
       ExtensionInstalledBubble::ANCHOR_PAGE_ACTION) {
     BrowserView* browser_view =
         BrowserView::GetBrowserViewForBrowser(browser());
     browser_view->GetLocationBarView()->SetPreviewEnabledPageAction(
         extensions::ExtensionActionManager::Get(browser()->profile())
             ->GetPageAction(*controller_->extension()),
         false);  // preview_enabled
   }
-  controller_ = nullptr;
   GetWidget()->Close();
 }
 
 base::string16 ExtensionInstalledBubbleView::GetWindowTitle() const {
   // Add the heading (for all options).
   base::string16 extension_name =
       base::UTF8ToUTF16(controller_->extension()->name());
   base::i18n::AdjustStringForLocaleDirection(&extension_name);
   return l10n_util::GetStringFUTF16(IDS_EXTENSION_INSTALLED_HEADING,
                                     extension_name);
@@ skipping 173 matching lines @@
             ->browser_actions();
     return !container->animating();
   }
   return true;
 }
 
 // Implemented here to create the platform specific instance of the BubbleUi.
 std::unique_ptr<BubbleUi> ExtensionInstalledBubble::BuildBubbleUi() {
   return base::WrapUnique(new ExtensionInstalledBubbleUi(this));
 }