Fix animation bug in ExtensionInfoBar would can result in orphaned instances in the view hierarchy

chrome/browser/extensions/extension_infobar_delegate.h

Index: chrome/browser/extensions/extension_infobar_delegate.h
diff --git a/chrome/browser/extensions/extension_infobar_delegate.h b/chrome/browser/extensions/extension_infobar_delegate.h
index 25e548fa0f298eea91ca668a543f1a39e45aa582..01174efc26d7dc0ce9fab8614f3daec8144f102c 100644
--- a/chrome/browser/extensions/extension_infobar_delegate.h
+++ b/chrome/browser/extensions/extension_infobar_delegate.h
@@ -33,6 +33,7 @@ class ExtensionInfoBarDelegate : public InfoBarDelegate,
   void set_observer(DelegateObserver* observer) { observer_ = observer; }
 
   // Overridden from InfoBarDelegate:
+  virtual void InfoBarDismissed() { closing_ = true; }
   virtual bool EqualsDelegate(InfoBarDelegate* delegate) const;
   virtual void InfoBarClosed();
   virtual InfoBar* CreateInfoBar();
@@ -48,6 +49,7 @@ class ExtensionInfoBarDelegate : public InfoBarDelegate,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
+  bool closing() { return closing_; }
  private:
   // The extension host we are showing the InfoBar for. The delegate needs to
   // own this since the InfoBar gets deleted and recreated when you switch tabs
@@ -64,6 +66,10 @@ class ExtensionInfoBarDelegate : public InfoBarDelegate,
 
   NotificationRegistrar registrar_;
 
+  // Whether we are currently animating to close. This is used to ignore
+  // ExtensionView::PreferredSizeChanged notifications.
+  bool closing_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionInfoBarDelegate);
 };