Add a second line of defense for receiving a bad message in the renderer.

content/browser/tab_contents/tab_contents.cc

 // Copyright (c) 2011 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 "content/browser/tab_contents/tab_contents.h"
 
 #include <cmath>
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
@@ skipping 555 matching lines @@
 }
 
 bool TabContents::NavigateToPendingEntry(
     NavigationController::ReloadType reload_type) {
   return NavigateToEntry(*controller_.pending_entry(), reload_type);
 }
 
 bool TabContents::NavigateToEntry(
     const NavigationEntry& entry,
     NavigationController::ReloadType reload_type) {
-  RenderViewHost* dest_render_view_host = render_manager_.Navigate(entry);
-  if (!dest_render_view_host)
-    return false;  // Unable to create the desired render view host.
-
   // The renderer will reject IPC messages with URLs longer than
   // this limit, so don't attempt to navigate with a longer URL.
   if (entry.url().spec().size() > content::kMaxURLChars)
     return false;
 
+  RenderViewHost* dest_render_view_host = render_manager_.Navigate(entry);
+  if (!dest_render_view_host)
+    return false;  // Unable to create the desired render view host.
+
   // For security, we should never send non-Web-UI URLs to a Web UI renderer.
   // Double check that here.
   int enabled_bindings = dest_render_view_host->enabled_bindings();
   bool is_allowed_in_web_ui_renderer = content::GetContentClient()->
       browser()->GetWebUIFactory()->IsURLAcceptableForWebUI(browser_context(),
                                                             entry.url());
   CHECK(!BindingsPolicy::is_web_ui_enabled(enabled_bindings) ||
         is_allowed_in_web_ui_renderer);
 
   // Tell DevTools agent that it is attached prior to the navigation.
@@ skipping 1363 matching lines @@
 
 void TabContents::set_encoding(const std::string& encoding) {
   encoding_ = content::GetContentClient()->browser()->
       GetCanonicalEncodingNameByAliasName(encoding);
 }
 
 void TabContents::CreateViewAndSetSizeForRVH(RenderViewHost* rvh) {
   RenderWidgetHostView* rwh_view = view()->CreateViewForWidget(rvh);
   rwh_view->SetSize(view()->GetContainerSize());
 }