Add feature for main frame before activation.

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 <stddef.h>
 #include <limits>
 #include <string>
 #include <utility>
@@ skipping 229 matching lines @@
     if (display_vsync_string == "gpu") {
       settings.renderer_settings.disable_display_vsync = true;
     } else if (display_vsync_string == "beginframe") {
       settings.wait_for_beginframe_interval = false;
     } else {
       settings.renderer_settings.disable_display_vsync = true;
       settings.wait_for_beginframe_interval = false;
     }
   }
   settings.main_frame_before_activation_enabled =
-      cmd->HasSwitch(cc::switches::kEnableMainFrameBeforeActivation) &&
-      !cmd->HasSwitch(cc::switches::kDisableMainFrameBeforeActivation);
+      cmd->HasSwitch(cc::switches::kEnableMainFrameBeforeActivation);
   settings.use_mouse_wheel_gestures = UseGestureBasedWheelScrolling();
 
   settings.default_tile_size = CalculateDefaultTileSize(device_scale_factor);
   if (cmd->HasSwitch(switches::kDefaultTileWidth)) {
     int tile_width = 0;
     GetSwitchValueAsInt(*cmd,
                         switches::kDefaultTileWidth,
                         1,
                         std::numeric_limits<int>::max(),
                         &tile_width);
@@ skipping 861 matching lines @@
 #endif
   return actual;
 }
 
 void RenderWidgetCompositor::SetPaintedDeviceScaleFactor(
     float device_scale) {
   layer_tree_host_->SetPaintedDeviceScaleFactor(device_scale);
 }
 
 }  // namespace content