Replace PruneAllButActive with PruneAllButVisible.

chrome/browser/ui/search/instant_controller.cc

 // Copyright 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 "chrome/browser/ui/search/instant_controller.h"
 
 #include <iterator>
 
 #include "base/metrics/histogram.h"
 #include "base/string_util.h"
@@ skipping 807 matching lines @@
     return false;
 
   if (type == INSTANT_COMMIT_FOCUS_LOST) {
     // Extended mode doesn't need or use the Cancel message.
     if (!extended_enabled_)
       overlay_->Cancel(last_omnibox_text_);
   } else if (type != INSTANT_COMMIT_NAVIGATED) {
     overlay_->Submit(last_omnibox_text_);
   }
 
+  // Make sure the overlay WebContents is in a valid state (i.e., has a last
+  // committed entry, no transient entry, and no existing pending entry).
   scoped_ptr<content::WebContents> overlay = overlay_->ReleaseContents();
+  if (!overlay || !overlay->GetController().CanPruneAllButVisible())
+    return false;
 
   // If the overlay page has navigated since the last Update(), we need to add
   // the navigation to history ourselves. Else, the page will navigate after
   // commit, and it will be added to history in the usual manner.
   const history::HistoryAddPageArgs& last_navigation =
       overlay_->last_navigation();
   if (!last_navigation.url.is_empty()) {
     content::NavigationEntry* entry = overlay->GetController().GetActiveEntry();
 
     // The last navigation should be the same as the active entry if the overlay
@@ skipping 19 matching lines @@
   HistoryService* history = HistoryServiceFactory::GetForProfile(
       Profile::FromBrowserContext(overlay->GetBrowserContext()),
       Profile::EXPLICIT_ACCESS);
   if (history) {
     history->AddPage(url_for_history_, base::Time::Now(), NULL, 0, GURL(),
                      history::RedirectList(), last_transition_type_,
                      history::SOURCE_BROWSED, false);
   }
 
   if (type == INSTANT_COMMIT_PRESSED_ALT_ENTER) {
-    overlay->GetController().PruneAllButActive();
+    CHECK(overlay->GetController().PruneAllButVisible());
   } else {
     content::WebContents* active_tab = browser_->GetActiveWebContents();
     AddSessionStorageHistogram(extended_enabled_, active_tab, overlay.get());
-    overlay->GetController().CopyStateFromAndPrune(
-        &active_tab->GetController());
+    CHECK(overlay->GetController().CopyStateFromAndPrune(
+              &active_tab->GetController()));
   }
 
   if (extended_enabled_) {
     // Adjust the search terms shown in the omnibox for this query. Hitting
     // ENTER searches for what the user typed, so use last_omnibox_text_.
     // Clicking on the overlay commits what is currently showing, so add in the
     // gray text in that case.
     if (type == INSTANT_COMMIT_FOCUS_LOST &&
         last_suggestion_.behavior == INSTANT_COMPLETE_NEVER) {
       // Update |last_omnibox_text_| so that the controller commits the proper
@@ skipping 947 matching lines @@
 
   result->transition = match.transition;
   result->relevance = match.relevance;
   result->autocomplete_match_index = autocomplete_match_index;
 
   DVLOG(1) << "    " << result->relevance << " " << result->type << " "
       << result->provider << " " << result->destination_url << " '"
       << result->description << "' '" << result->search_query << "' "
       << result->transition <<  " " << result->autocomplete_match_index;
 }