Added experiment for changing viewport scroll ordering.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 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/renderer/gpu/render_widget_compositor.h"
 
 #include <limits>
 #include <string>
 
 #include "base/command_line.h"
@@ skipping 344 matching lines @@
     const int kMinSlowDownScaleFactor = 0;
     const int kMaxSlowDownScaleFactor = INT_MAX;
     GetSwitchValueAsInt(
         *cmd,
         cc::switches::kSlowDownRasterScaleFactor,
         kMinSlowDownScaleFactor,
         kMaxSlowDownScaleFactor,
         &settings.initial_debug_state.slow_down_raster_scale_factor);
   }
 
+  settings.invert_viewport_scroll_order =
+      cmd->HasSwitch(switches::kInvertViewportScrollOrder);
+
   if (cmd->HasSwitch(cc::switches::kMaxUnusedResourceMemoryUsagePercentage)) {
     int max_unused_resource_memory_percentage;
     if (GetSwitchValueAsInt(
             *cmd,
             cc::switches::kMaxUnusedResourceMemoryUsagePercentage,
             0, 100,
             &max_unused_resource_memory_percentage)) {
       settings.max_unused_resource_memory_percentage =
           max_unused_resource_memory_percentage;
     }
@@ skipping 598 matching lines @@
     return;
   provider->ContextGL()->RateLimitOffscreenContextCHROMIUM();
 }
 
 void RenderWidgetCompositor::SetSurfaceIdNamespace(
     uint32_t surface_id_namespace) {
   layer_tree_host_->set_surface_id_namespace(surface_id_namespace);
 }
 
 }  // namespace content