Add a flag to disable threaded scrolling

content/renderer/render_view_impl.cc

 // Copyright (c) 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 "content/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/auto_reset.h"
@@ skipping 741 matching lines @@
     CompleteInit();
   }
 
   g_view_map.Get().insert(std::make_pair(webview(), this));
   g_routing_id_view_map.Get().insert(std::make_pair(routing_id_, this));
   webview()->setDeviceScaleFactor(device_scale_factor_);
   webview()->settings()->setPreferCompositingToLCDTextEnabled(
       PreferCompositingToLCDText(device_scale_factor_));
   webview()->settings()->setAcceleratedCompositingForTransitionEnabled(
       ShouldUseTransitionCompositing(device_scale_factor_));
+  webview()->settings()->setThreadedScrollingEnabled(
+      !command_line.HasSwitch(switches::kDisableThreadedScrolling));
 
   ApplyWebPreferences(webkit_preferences_, webview());
 
   webview()->settings()->setAllowConnectingInsecureWebSocket(
       command_line.HasSwitch(switches::kAllowInsecureWebSocketFromHttpsOrigin));
 
   RenderFrameProxy* proxy = NULL;
   if (params->proxy_routing_id != MSG_ROUTING_NONE) {
     CHECK(params->swapped_out);
     proxy = RenderFrameProxy::CreateProxyToReplaceFrame(
@@ skipping 3442 matching lines @@
     std::vector<gfx::Size> sizes;
     ConvertToFaviconSizes(icon_urls[i].sizes(), &sizes);
     if (!url.isEmpty())
       urls.push_back(
           FaviconURL(url, ToFaviconType(icon_urls[i].iconType()), sizes));
   }
   SendUpdateFaviconURL(urls);
 }
 
 }  // namespace content