Add a flag for enabling/disabling the new accelerated scrolling path

content/browser/web_contents/web_contents_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/browser/web_contents/web_contents_impl.h"
 
 #include <utility>
 
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
@@ skipping 515 matching lines @@
     prefs.accelerated_compositing_for_scrollable_frames_enabled = true;
   if (command_line.HasSwitch(switches::kDisableAcceleratedScrollableFrames))
     prefs.accelerated_compositing_for_scrollable_frames_enabled = false;
 
   prefs.composited_scrolling_for_frames_enabled = false;
   if (command_line.HasSwitch(switches::kEnableCompositedScrollingForFrames))
     prefs.composited_scrolling_for_frames_enabled = true;
   if (command_line.HasSwitch(switches::kDisableCompositedScrollingForFrames))
     prefs.composited_scrolling_for_frames_enabled = false;
 
+  prefs.universal_accelerated_compositing_for_overflow_scroll_enabled = false;
+  if (command_line.HasSwitch(
+          switches::kEnableUniversalAcceleratedOverflowScroll))
+    prefs.universal_accelerated_compositing_for_overflow_scroll_enabled = true;
+  if (command_line.HasSwitch(
+          switches::kDisableUniversalAcceleratedOverflowScroll))
+    prefs.universal_accelerated_compositing_for_overflow_scroll_enabled = false;
+
   prefs.show_paint_rects =
       command_line.HasSwitch(switches::kShowPaintRects);
   prefs.accelerated_compositing_enabled =
       GpuProcessHost::gpu_enabled() &&
       !command_line.HasSwitch(switches::kDisableAcceleratedCompositing);
   prefs.force_compositing_mode =
       content::IsForceCompositingModeEnabled() &&
       !command_line.HasSwitch(switches::kDisableForceCompositingMode);
   prefs.accelerated_2d_canvas_enabled =
       GpuProcessHost::gpu_enabled() &&
@@ skipping 3266 matching lines @@
 }
 
 void WebContentsImpl::OnFrameRemoved(
     RenderViewHostImpl* render_view_host,
     int64 frame_id) {
    FOR_EACH_OBSERVER(WebContentsObserver, observers_,
                      FrameDetached(render_view_host, frame_id));
 }
 
 }  // namespace content