Add a tracing line to ApplyWebPreferences. This is a potentially very expensive operation.

content/renderer/web_preferences.cc

 // Copyright 2013 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/public/renderer/web_preferences.h"
 
+#include "base/debug/trace_event.h"
 #include "base/strings/utf_string_conversions.h"
 #include "content/renderer/net_info_helper.h"
 #include "third_party/WebKit/public/platform/WebConnectionType.h"
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/platform/WebURL.h"
 #include "third_party/WebKit/public/web/WebKit.h"
 #include "third_party/WebKit/public/web/WebNetworkStateNotifier.h"
 #include "third_party/WebKit/public/web/WebRuntimeFeatures.h"
 #include "third_party/WebKit/public/web/WebSettings.h"
 #include "third_party/WebKit/public/web/WebView.h"
@@ skipping 90 matching lines @@
     if (script >= 0 && script < USCRIPT_CODE_LIMIT) {
       UScriptCode code = static_cast<UScriptCode>(script);
       (*setter)(settings, it->second, GetScriptForWebSettings(code));
     }
   }
 }
 
 }  // namespace
 
 void ApplyWebPreferences(const WebPreferences& prefs, WebView* web_view) {
+  TRACE_EVENT0("renderer", "ApplyWebPreferences");
   WebSettings* settings = web_view->settings();
   ApplyFontsFromMap(prefs.standard_font_family_map,
                     setStandardFontFamilyWrapper, settings);
   ApplyFontsFromMap(prefs.fixed_font_family_map,
                     setFixedFontFamilyWrapper, settings);
   ApplyFontsFromMap(prefs.serif_font_family_map,
                     setSerifFontFamilyWrapper, settings);
   ApplyFontsFromMap(prefs.sans_serif_font_family_map,
                     setSansSerifFontFamilyWrapper, settings);
   ApplyFontsFromMap(prefs.cursive_font_family_map,
@@ skipping 204 matching lines @@
   settings->setPinchVirtualViewportEnabled(
       prefs.pinch_virtual_viewport_enabled);
 
   settings->setPinchOverlayScrollbarThickness(
       prefs.pinch_overlay_scrollbar_thickness);
   settings->setUseSolidColorScrollbars(prefs.use_solid_color_scrollbars);
   settings->setCompositorTouchHitTesting(prefs.compositor_touch_hit_testing);
 }
 
 }  // namespace content