Mac: Fix renderer idle cpu usage regression.

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 771 matching lines @@
 }
 
 bool TabContents::NavigateToPendingEntry(
     NavigationController::ReloadType reload_type) {
   const NavigationEntry& entry = *controller_.pending_entry();
 
   RenderViewHost* dest_render_view_host = render_manager_.Navigate(entry);
   if (!dest_render_view_host)
     return false;  // Unable to create the desired render view host.
 
-  if (delegate_ && delegate_->ShouldEnablePreferredSizeNotifications())
-    dest_render_view_host->EnablePreferredSizeChangedMode();
+  if (delegate_ && delegate_->ShouldEnablePreferredSizeNotifications()) {
+    dest_render_view_host->EnablePreferredSizeChangedMode(
+        kPreferredSizeWidth | kPreferredSizeHeightThisIsSlow);
+  }
 
   // For security, we should never send non-DOM-UI URLs (other than about:blank)
   // to a DOM UI renderer.  Double check that here.
   int enabled_bindings = dest_render_view_host->enabled_bindings();
   bool is_allowed_in_dom_ui_renderer =
       DOMUIFactory::UseDOMUIForURL(entry.url()) ||
       entry.url() == GURL(chrome::kAboutBlankURL);
   CHECK(!BindingsPolicy::is_dom_ui_enabled(enabled_bindings) ||
         is_allowed_in_dom_ui_renderer);
 
@@ skipping 2368 matching lines @@
   AddInfoBar(new SavePasswordInfoBarDelegate(this, form_to_save));
 }
 
 Profile* TabContents::GetProfileForPasswordManager() {
   return profile();
 }
 
 bool TabContents::DidLastPageLoadEncounterSSLErrors() {
   return controller().ssl_manager()->ProcessedSSLErrorFromRequest();
 }