Don't clear controller_ in ExtensionInstalledBubbleView::CloseBubble.

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

Index: chrome/browser/ui/views/extensions/extension_installed_bubble_view.cc
diff --git a/chrome/browser/ui/views/extensions/extension_installed_bubble_view.cc b/chrome/browser/ui/views/extensions/extension_installed_bubble_view.cc
index 85331a2314e33042bda8588e73a22e6ae9e7ca33..d0cf37393b8aae346293a4b4cabba8106e2a7271 100644
--- a/chrome/browser/ui/views/extensions/extension_installed_bubble_view.cc
+++ b/chrome/browser/ui/views/extensions/extension_installed_bubble_view.cc
@@ -157,7 +157,9 @@ void ExtensionInstalledBubbleView::UpdateAnchorView() {
 }
 
 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());
@@ -166,7 +168,6 @@ void ExtensionInstalledBubbleView::CloseBubble() {
             ->GetPageAction(*controller_->extension()),
         false);  // preview_enabled
   }
-  controller_ = nullptr;
   GetWidget()->Close();
 }