Replace PruneAllButActive with PruneAllButVisible.

chrome/browser/ui/browser_commands.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_commands.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/utf_string_conversions.h"
@@ skipping 991 matching lines @@
 void ViewSource(Browser* browser,
                 WebContents* contents,
                 const GURL& url,
                 const std::string& content_state) {
   content::RecordAction(UserMetricsAction("ViewSource"));
   DCHECK(contents);
 
   // Note that Clone does not copy the pending or transient entries, so the
   // active entry in view_source_contents will be the last committed entry.
   WebContents* view_source_contents = contents->Clone();
-  view_source_contents->GetController().PruneAllButActive();
+  DCHECK(view_source_contents->GetController().CanPruneAllButVisible());
+  if (!view_source_contents->GetController().PruneAllButVisible())
+    return;
   NavigationEntry* active_entry =
       view_source_contents->GetController().GetActiveEntry();
   if (!active_entry)
     return;
 
   GURL view_source_url = GURL(kViewSourceScheme + std::string(":") +
       url.spec());
   active_entry->SetVirtualURL(view_source_url);
 
   // Do not restore scroller position.
@@ skipping 77 matching lines @@
           Browser::TYPE_POPUP, app_name, gfx::Rect(), browser->profile(),
           browser->host_desktop_type()));
   app_browser->tab_strip_model()->AppendWebContents(contents, true);
 
   contents->GetMutableRendererPrefs()->can_accept_load_drops = false;
   contents->GetRenderViewHost()->SyncRendererPrefs();
   app_browser->window()->Show();
 }
 
 }  // namespace chrome