Add CompositingReasons to compositor layer types.

cc/layers/layer.cc

Index: cc/layers/layer.cc
diff --git a/cc/layers/layer.cc b/cc/layers/layer.cc
index be1efd04677d614dc646396242e16e6211a2405a..633125bb9ceaa3c99c516b9aed32f81eb66ac057 100644
--- a/cc/layers/layer.cc
+++ b/cc/layers/layer.cc
@@ -40,6 +40,7 @@ Layer::Layer()
       have_wheel_event_handlers_(false),
       anchor_point_(0.5f, 0.5f),
       background_color_(0),
+      compositing_reasons_(WebKit::CompositingReasonUnknown),
       opacity_(1.f),
       anchor_point_z_(0.f),
       is_container_for_fixed_position_layers_(false),
@@ -646,6 +647,7 @@ void Layer::PushPropertiesTo(LayerImpl* layer) {
   layer->SetContentBounds(content_bounds());
   layer->SetContentsScale(contents_scale_x(), contents_scale_y());
   layer->SetDebugName(debug_name_);
+  layer->SetCompositingReasons(compositing_reasons_);
   layer->SetDoubleSided(double_sided_);
   layer->SetDrawCheckerboardForMissingTiles(
       draw_checkerboard_for_missing_tiles_);
@@ -747,6 +749,11 @@ void Layer::SetDebugName(const std::string& debug_name) {
   SetNeedsCommit();
 }
 
+void Layer::SetCompositingReasons(WebKit::WebCompositingReasons reasons) {

[danakj, 2013/05/15 14:02:43]

Add this to the layer unittests?

+  compositing_reasons_ = reasons;
+  SetNeedsCommit();
+}
+
 void Layer::CreateRenderSurface() {
   DCHECK(!draw_properties_.render_surface);
   draw_properties_.render_surface = make_scoped_ptr(new RenderSurface(this));