Mac: Fix renderer idle cpu usage regression.

chrome/renderer/render_view.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/renderer/render_view.h"
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
@@ skipping 3857 matching lines @@
 void RenderView::OnEnableViewSourceMode() {
   if (!webview())
     return;
   WebFrame* main_frame = webview()->mainFrame();
   if (!main_frame)
     return;
 
   main_frame->enableViewSourceMode(true);
 }
 
-void RenderView::OnEnablePreferredSizeChangedMode() {
+void RenderView::OnEnablePreferredSizeChangedMode(int flags) {
+  DCHECK(flags != kPreferredSizeNothing);
   if (send_preferred_size_changes_)
     return;
+  send_preferred_size_changes_ = true;
 
-  send_preferred_size_changes_ = true;
-  preferred_size_change_timer_.Start(TimeDelta::FromMilliseconds(10), this,
-                                     &RenderView::CheckPreferredSize);
+  // WebKit doesn't send a notification of the effective height of the page
+  // changes, so poll for it.
+  // TODO: Add a notification for this to WebKit, remove polling. After that's
+  // done, rename kPreferredSizeHeightThisIsSlow to kPreferredSizeHeight.
+  // http://crbug.com/44850
+  if (flags & kPreferredSizeHeightThisIsSlow) {
+    preferred_size_change_timer_.Start(TimeDelta::FromMilliseconds(10), this,
+                                       &RenderView::CheckPreferredSize);
+  }
 }
 
 void RenderView::OnDisableScrollbarsForSmallWindows(
     const gfx::Size& disable_scrollbar_size_limit) {
   disable_scrollbars_size_limit_ = disable_scrollbar_size_limit;
 }
 
 void RenderView::OnSetRendererPrefs(const RendererPreferences& renderer_prefs) {
   renderer_preferences_ = renderer_prefs;
   UpdateFontRenderingFromRendererPrefs();
@@ skipping 1128 matching lines @@
 
     if (last_top_level_navigation_page_id_ != page_id_ &&
         // Not interested in reloads.
         type != WebKit::WebNavigationTypeReload &&
         type != WebKit::WebNavigationTypeFormSubmitted) {
       return true;
     }
   }
   return false;
 }