Replace PruneAllButActive with PruneAllButVisible.

chrome/browser/ui/browser_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/browser_instant_controller.h"
 
 #include "base/bind.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/extensions/extension_web_ui.h"
@@ skipping 82 matching lines @@
     // If there is an extension overriding the NTP do not use the Instant NTP.
     return false;
   }
 
   scoped_ptr<content::WebContents> instant_ntp = instant_.ReleaseNTPContents();
   if (!instant_ntp)
     return false;
 
   *target_contents = instant_ntp.get();
   if (source_contents) {
-    instant_ntp->GetController().CopyStateFromAndPrune(
-        &source_contents->GetController());
-    ReplaceWebContentsAt(
-        browser_->tab_strip_model()->GetIndexOfWebContents(source_contents),
-        instant_ntp.Pass());
+    // If the Instant NTP hasn't yet committed an entry, we can't call
+    // CopyStateFromAndPrune.  Instead, load the Local NTP URL directly in the
+    // source contents.
+    // TODO(sreeram): Always using the local URL is wrong in the case of the
+    // first tab in a window where we might want to use the remote URL. Fix.
+    if (!instant_ntp->GetController().CanPruneAllButVisible()) {
+      source_contents->GetController().LoadURL(chrome::GetLocalInstantURL(
+          profile()), content::Referrer(), content::PAGE_TRANSITION_GENERATED,
+          std::string());
+      *target_contents = source_contents;
+    } else {
+      instant_ntp->GetController().CopyStateFromAndPrune(
+          &source_contents->GetController());
+      ReplaceWebContentsAt(
+          browser_->tab_strip_model()->GetIndexOfWebContents(source_contents),
+          instant_ntp.Pass());
+    }
   } else {
-    instant_ntp->GetController().PruneAllButActive();
+    // If the Instant NTP hasn't yet committed an entry, we can't call
+    // PruneAllButVisible.  In that case, there shouldn't be any entries to
+    // prune anyway.
+    if (instant_ntp->GetController().CanPruneAllButVisible())
+      instant_ntp->GetController().PruneAllButVisible();
+    else
+      CHECK(!instant_ntp->GetController().GetLastCommittedEntry());
+
     // If |source_contents| is NULL, then the caller is responsible for
     // inserting instant_ntp into the tabstrip and will take ownership.
     ignore_result(instant_ntp.release());
   }
   return true;
 }
 
 bool BrowserInstantController::OpenInstant(WindowOpenDisposition disposition) {
   // Unsupported dispositions.
   if (disposition == NEW_BACKGROUND_TAB || disposition == NEW_WINDOW)
@@ skipping 276 matching lines @@
     if (!instant_service->IsInstantProcess(
             contents->GetRenderProcessHost()->GetID()))
       continue;
 
     // Reload the contents to ensure that it gets assigned to a non-priviledged
     // renderer.
     contents->GetController().Reload(false);
   }
   instant_.OnDefaultSearchProviderChanged();
 }