Band-aid around an unexplained crasher.

chrome/browser/tab_contents/tab_contents.cc

 // Copyright (c) 2010 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 "chrome/browser/tab_contents/tab_contents.h"
 
 #if defined(OS_CHROMEOS)
 // For GdkScreen
 #include <gdk/gdk.h>
 #endif  // defined(OS_CHROMEOS)
@@ skipping 1088 matching lines @@
   }
 
   std::vector<InfoBarDelegate*>::iterator it =
       find(infobar_delegates_.begin(), infobar_delegates_.end(), delegate);
   if (it != infobar_delegates_.end()) {
     InfoBarDelegate* delegate = *it;
     NotificationService::current()->Notify(
         NotificationType::TAB_CONTENTS_INFOBAR_REMOVED,
         Source<TabContents>(this),
         Details<InfoBarDelegate>(delegate));
-    infobar_delegates_.erase(it);
 
-    // Remove ourselves as an observer if we are tracking no more InfoBars.
-    if (infobar_delegates_.empty()) {
-      registrar_.Remove(this, NotificationType::NAV_ENTRY_COMMITTED,
-                        Source<NavigationController>(&controller_));
+    // Just to be safe, make sure the delegate was not removed by an observer.
+    it = find(infobar_delegates_.begin(), infobar_delegates_.end(), delegate);
+    if (it != infobar_delegates_.end()) {
+      infobar_delegates_.erase(it);
+      // Remove ourselves as an observer if we are tracking no more InfoBars.
+      if (infobar_delegates_.empty()) {
+        registrar_.Remove(this, NotificationType::NAV_ENTRY_COMMITTED,
+                          Source<NavigationController>(&controller_));
+      }
+    } else {
+      // If you hit this NOTREACHED, please comment in bug
+      // http://crbug.com/50428 how you got there.
+      NOTREACHED();
     }
   }
 }
 
 void TabContents::ReplaceInfoBar(InfoBarDelegate* old_delegate,
                                  InfoBarDelegate* new_delegate) {
   if (delegate_ && !delegate_->infobars_enabled()) {
     new_delegate->InfoBarClosed();
     return;
   }
 
   std::vector<InfoBarDelegate*>::iterator it =
       find(infobar_delegates_.begin(), infobar_delegates_.end(), old_delegate);
   DCHECK(it != infobar_delegates_.end());
 
   // Notify the container about the change of plans.
   scoped_ptr<std::pair<InfoBarDelegate*, InfoBarDelegate*> > details(
     new std::pair<InfoBarDelegate*, InfoBarDelegate*>(
         old_delegate, new_delegate));
   NotificationService::current()->Notify(
       NotificationType::TAB_CONTENTS_INFOBAR_REPLACED,
       Source<TabContents>(this),
       Details<std::pair<InfoBarDelegate*, InfoBarDelegate*> >(details.get()));
 
-  // Remove the old one.
-  infobar_delegates_.erase(it);
+  // Just to be safe, make sure the delegate was not removed by an observer.
+  it = find(infobar_delegates_.begin(), infobar_delegates_.end(), old_delegate);
+  if (it != infobar_delegates_.end()) {
+    // Remove the old one.
+    infobar_delegates_.erase(it);
+  } else {
+    // If you hit this NOTREACHED, please comment in bug
+    // http://crbug.com/50428 how you got there.
+    NOTREACHED();
+  }
 
   // Add the new one.
+  DCHECK(find(infobar_delegates_.begin(),
+              infobar_delegates_.end(), new_delegate) ==
+         infobar_delegates_.end());
   infobar_delegates_.push_back(new_delegate);
 }
 
 bool TabContents::ShouldShowBookmarkBar() {
   if (showing_interstitial_page())
     return false;
 
   // See GetDOMUIForCurrentState() comment for more info. This case is very
   // similar, but for non-first loads, we want to use the committed entry. This
   // is so the bookmarks bar disappears at the same time the page does.
@@ skipping 342 matching lines @@
 void TabContents::ExpireInfoBars(
     const NavigationController::LoadCommittedDetails& details) {
   // Only hide InfoBars when the user has done something that makes the main
   // frame load. We don't want various automatic or subframe navigations making
   // it disappear.
   if (!details.is_user_initiated_main_frame_load())
     return;
 
   for (int i = infobar_delegate_count() - 1; i >= 0; --i) {
     InfoBarDelegate* delegate = GetInfoBarDelegateAt(i);
+    if (!delegate) {
+      // If you hit this NOTREACHED, please comment in bug
+      // http://crbug.com/50428 how you got there.
+      NOTREACHED();
+      continue;
+    }
+
     if (delegate->ShouldExpire(details))
       RemoveInfoBar(delegate);
   }
 }
 
 DOMUI* TabContents::GetDOMUIForCurrentState() {
   // When there is a pending navigation entry, we want to use the pending DOMUI
   // that goes along with it to control the basic flags. For example, we want to
   // show the pending URL in the URL bar, so we want the display_url flag to
   // be from the pending entry.
@@ skipping 1785 matching lines @@
   AddInfoBar(new SavePasswordInfoBarDelegate(this, form_to_save));
 }
 
 Profile* TabContents::GetProfileForPasswordManager() {
   return profile();
 }
 
 bool TabContents::DidLastPageLoadEncounterSSLErrors() {
   return controller().ssl_manager()->ProcessedSSLErrorFromRequest();
 }