cc: Allow sending BeginMainFrame before draw or activation

cc/trees/layer_tree_settings.cc

Index: cc/trees/layer_tree_settings.cc
diff --git a/cc/trees/layer_tree_settings.cc b/cc/trees/layer_tree_settings.cc
index 0ace95a6868ec18abe3501083c79cdc39dd0cca0..b60ddb51923bb114350013fc7596fe2921cc72eb 100644
--- a/cc/trees/layer_tree_settings.cc
+++ b/cc/trees/layer_tree_settings.cc
@@ -18,6 +18,8 @@ LayerTreeSettings::LayerTreeSettings()
       throttle_frame_production(true),
       begin_impl_frame_scheduling_enabled(false),
       deadline_scheduling_enabled(true),
+      start_commit_before_draw_enabled(true),
+      start_commit_before_activate_enabled(false),
       using_synchronous_renderer_compositor(false),
       per_tile_painting_enabled(false),
       partial_swap_enabled(false),
@@ -57,8 +59,7 @@ LayerTreeSettings::LayerTreeSettings()
       ignore_root_layer_flings(false),
       use_rgba_4444_textures(false),
       touch_hit_testing(true),
-      texture_id_allocation_chunk_size(64) {
-}
+      texture_id_allocation_chunk_size(64) {}
 
 LayerTreeSettings::~LayerTreeSettings() {}