cc: Start commit early and block on tree activation

cc/trees/layer_tree_settings.cc

 // Copyright 2011 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 "cc/trees/layer_tree_settings.h"
 
 #include <limits>
 
 #include "base/command_line.h"
 #include "base/logging.h"
@@ skipping 25 matching lines @@
       use_memory_management(true),
       timeout_and_draw_when_animation_checkerboards(true),
       layer_transforms_should_scale_layer_contents(false),
       minimum_contents_scale(0.0625f),
       low_res_contents_scale_factor(0.125f),
       top_controls_height(0.f),
       top_controls_show_threshold(0.5f),
       top_controls_hide_threshold(0.5f),
       refresh_rate(60.0),
       max_partial_texture_updates(std::numeric_limits<size_t>::max()),
-      num_raster_threads(1),
+      num_raster_threads(4),
       default_tile_size(gfx::Size(256, 256)),
       max_untiled_layer_size(gfx::Size(512, 512)),
       minimum_occlusion_tracking_size(gfx::Size(160, 160)),
       use_pinch_zoom_scrollbars(false),
       use_pinch_virtual_viewport(false),
       // At 256x256 tiles, 128 tiles cover an area of 2048x4096 pixels.
       max_tiles_for_interest_area(128),
       max_unused_resource_memory_percentage(100),
       highp_threshold_min(0),
       force_direct_layer_drawing(false),
       strict_layer_property_change_checking(false),
       use_map_image(false),
       compositor_name("ChromiumCompositor"),
       ignore_root_layer_flings(false) {
   // TODO(danakj): Renable surface caching when we can do it more realiably.
   // crbug.com/170713
   cache_render_pass_contents = false;
 }
 
 LayerTreeSettings::~LayerTreeSettings() {}
 
 }  // namespace cc