Add support for (de)serializing LayerTreeHost.

cc/trees/layer_tree_host.cc

Index: cc/trees/layer_tree_host.cc
diff --git a/cc/trees/layer_tree_host.cc b/cc/trees/layer_tree_host.cc
index 70740935217a4482d62abd598cb54e879017a7d4..1508cc448a6140c00c16be75e6a6723986aa816d 100644
--- a/cc/trees/layer_tree_host.cc
+++ b/cc/trees/layer_tree_host.cc
@@ -36,8 +36,11 @@
 #include "cc/layers/heads_up_display_layer_impl.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_iterator.h"
+#include "cc/layers/layer_proto_converter.h"
 #include "cc/layers/layer_settings.h"
 #include "cc/layers/painted_scrollbar_layer.h"
+#include "cc/proto/gfx_conversions.h"
+#include "cc/proto/layer_tree_host.pb.h"
 #include "cc/resources/ui_resource_request.h"
 #include "cc/scheduler/begin_frame_source.h"
 #include "cc/trees/draw_property_utils.h"
@@ -1276,4 +1279,167 @@ bool LayerTreeHost::IsThreaded() const {
   return compositor_mode_ == CompositorMode::Threaded;
 }
 
+void LayerTreeHost::ToProtobufForCommit(proto::LayerTreeHost* proto) const {
+  // Not all fields are serialized, as they are eiher not needed for a commit,
+  // or implementation isn't ready yet. The members in the latter category
+  // are listed below.
+  // Things not supported include animations, UI resources, instrumentation
+  // of stats, histograms. The output surfaces are only valid on the client-side
+  // so they are therefore not serialized. The LayerTreeSettings are needed
+  // during construction of the LayerTreeHost, so they should be serialized
+  // outside of the LayerTreeHost serialization. SwapPromise are currently not

[vmpstr, 2016/01/11 22:06:29]

Can you make all of the different things point form so it's easier to read?

[nyquist, 2016/01/13 01:34:11]

Done.

+  // supported. The bitmap and GPU memory related items are also not serialized.
+  // The |visible_| flag will be controlled from the client separately and will
+  // need special handling outside of the serialization of the LayerTreeHost.
+  // SwapPromise are skipped because they are mostly used for perf measurements.
+  // TODO(nyquist): Figure out how to support animations.

[vmpstr, 2016/01/11 22:06:30]

crbug?

[nyquist, 2016/01/13 01:34:11]

OK with reusing the one for animationcontroller?
https://code.google.com/p/chromium/issues/detail?id=570376

+  proto->set_needs_full_tree_sync(needs_full_tree_sync_);
+  proto->set_needs_meta_info_recomputation(needs_meta_info_recomputation_);
+  proto->set_source_frame_number(source_frame_number_);
+  proto->set_meta_information_sequence_number(
+      meta_information_sequence_number_);
+  LayerProtoConverter::SerializeLayerHierarchy(root_layer_,
+                                               proto->mutable_root_layer());
+  LayerProtoConverter::SerializeLayerProperties(root_layer_.get(),
+                                                proto->mutable_layer_updates());
+  proto->set_hud_layer_id(hud_layer_ ? hud_layer_->id() : Layer::INVALID_ID);
+  debug_state_.ToProtobuf(proto->mutable_debug_state());
+  SizeToProto(device_viewport_size_, proto->mutable_device_viewport_size());
+  proto->set_top_controls_shrink_blink_size(top_controls_shrink_blink_size_);
+  proto->set_top_controls_height(top_controls_height_);
+  proto->set_top_controls_shown_ratio(top_controls_shown_ratio_);
+  proto->set_device_scale_factor(device_scale_factor_);
+  proto->set_painted_device_scale_factor(painted_device_scale_factor_);
+  proto->set_page_scale_factor(page_scale_factor_);
+  proto->set_min_page_scale_factor(min_page_scale_factor_);
+  proto->set_max_page_scale_factor(max_page_scale_factor_);
+  Vector2dFToProto(elastic_overscroll_, proto->mutable_elastic_overscroll());
+  proto->set_has_gpu_rasterization_trigger(has_gpu_rasterization_trigger_);
+  proto->set_content_is_suitable_for_gpu_rasterization(
+      content_is_suitable_for_gpu_rasterization_);
+  proto->set_background_color(background_color_);
+  proto->set_has_transparent_background(has_transparent_background_);
+  proto->set_in_paint_layer_contents(in_paint_layer_contents_);
+  proto->set_id(id_);
+  proto->set_next_commit_forces_redraw(next_commit_forces_redraw_);
+
+  // Viewport layers.
+  proto->set_overscroll_elasticity_layer_id(
+      overscroll_elasticity_layer_ ? overscroll_elasticity_layer_->id()
+                                   : Layer::INVALID_ID);
+  proto->set_page_scale_layer_id(page_scale_layer_ ? page_scale_layer_->id()
+                                                   : Layer::INVALID_ID);
+  proto->set_inner_viewport_scroll_layer_id(
+      inner_viewport_scroll_layer_ ? inner_viewport_scroll_layer_->id()
+                                   : Layer::INVALID_ID);
+  proto->set_outer_viewport_scroll_layer_id(
+      outer_viewport_scroll_layer_ ? outer_viewport_scroll_layer_->id()
+                                   : Layer::INVALID_ID);
+
+  LayerSelectionToProtobuf(selection_, proto->mutable_selection());

[vmpstr, 2016/01/11 22:06:30]

I'm a little bit sad that some things are out of line FooToProtobuf functions
and some are foo.ToProtobuf functions. Can you file a general bug to take a look
at this and possibly unify the convention?

[nyquist, 2016/01/13 01:34:11]

Agreed. See crbug.com/548432 which is tracking that effort.

+  property_trees_.ToProtobuf(proto->mutable_property_trees());
+  proto->set_surface_id_namespace(surface_id_namespace_);
+  proto->set_next_surface_sequence(next_surface_sequence_);
+}
+
+void LayerTreeHost::FromProtobufForCommit(const proto::LayerTreeHost& proto) {
+  needs_full_tree_sync_ = proto.needs_full_tree_sync();
+  needs_meta_info_recomputation_ = proto.needs_meta_info_recomputation();
+  source_frame_number_ = proto.source_frame_number();
+  meta_information_sequence_number_ = proto.meta_information_sequence_number();
+
+  // Layer hierarchy.
+  scoped_refptr<Layer> new_root_layer =
+      LayerProtoConverter::DeserializeLayerHierarchy(root_layer_,
+                                                     proto.root_layer());
+  if (root_layer_ != new_root_layer) {
+    root_layer_->SetLayerTreeHost(nullptr);
+    root_layer_ = new_root_layer;
+    root_layer_->SetLayerTreeHost(this);
+  }

[vmpstr, 2016/01/11 22:06:30]

blank line after this please

[nyquist, 2016/01/13 01:34:11]

Done.

+  layer_id_map_.clear();

[vmpstr, 2016/01/11 22:06:30]

// Populate layer_id_map_ with the new layers.

[nyquist, 2016/01/13 01:34:11]

Done.

+  LayerTreeHostCommon::CallFunctionForSubtree(
+      root_layer(),
+      [this](Layer* layer) { layer_id_map_[layer->id()] = layer; });
+
+  LayerProtoConverter::DeserializeLayerProperties(root_layer_.get(),
+                                                  proto.layer_updates());
+
+  if (hud_layer_)
+    hud_layer_->SetLayerTreeHost(nullptr);

[vmpstr, 2016/01/11 22:06:30]

blank line after this please

[nyquist, 2016/01/13 01:34:11]

Done.

+  if (proto.hud_layer_id() == Layer::INVALID_ID) {

[vmpstr, 2016/01/11 22:06:30]

Should we check if it's the same layer id to avoid work?

[nyquist, 2016/01/13 01:34:11]

Absolutely! Otherwise this apparently has a bug when we try to run the whole
system, as SetLayerTreeHost might delete it from the map.

+    hud_layer_ = nullptr;
+  } else {
+    DCHECK(layer_id_map_.find(proto.hud_layer_id()) != layer_id_map_.end());
+    hud_layer_ =
+        static_cast<HeadsUpDisplayLayer*>(layer_id_map_[proto.hud_layer_id()]);
+  }
+
+  debug_state_.FromProtobuf(proto.debug_state());
+  device_viewport_size_ = ProtoToSize(proto.device_viewport_size());
+  top_controls_shrink_blink_size_ = proto.top_controls_shrink_blink_size();
+  top_controls_height_ = proto.top_controls_height();
+  top_controls_shown_ratio_ = proto.top_controls_shown_ratio();
+  device_scale_factor_ = proto.device_scale_factor();
+  painted_device_scale_factor_ = proto.painted_device_scale_factor();
+  page_scale_factor_ = proto.page_scale_factor();
+  min_page_scale_factor_ = proto.min_page_scale_factor();
+  max_page_scale_factor_ = proto.max_page_scale_factor();
+  elastic_overscroll_ = ProtoToVector2dF(proto.elastic_overscroll());
+  has_gpu_rasterization_trigger_ = proto.has_gpu_rasterization_trigger();
+  content_is_suitable_for_gpu_rasterization_ =
+      proto.content_is_suitable_for_gpu_rasterization();
+  background_color_ = proto.background_color();
+  has_transparent_background_ = proto.has_transparent_background();
+  in_paint_layer_contents_ = proto.in_paint_layer_contents();
+  id_ = proto.id();
+  next_commit_forces_redraw_ = proto.next_commit_forces_redraw();
+
+  // Viewport layers.
+  if (overscroll_elasticity_layer_)

[vmpstr, 2016/01/11 22:06:30]

Same comment for all these layers as for the hud layer. Also can you move either
the hud layer thing here or all of the layers up? Just to group things up
better, or is there some dependency that isn't obvious?

[nyquist, 2016/01/13 01:34:11]

Done.

+    overscroll_elasticity_layer_->SetLayerTreeHost(nullptr);
+  if (proto.overscroll_elasticity_layer_id() == Layer::INVALID_ID) {
+    overscroll_elasticity_layer_ = nullptr;
+  } else {
+    DCHECK(layer_id_map_.find(proto.overscroll_elasticity_layer_id()) !=
+           layer_id_map_.end());
+    overscroll_elasticity_layer_ =
+        layer_id_map_[proto.overscroll_elasticity_layer_id()];
+  }
+  if (page_scale_layer_)
+    page_scale_layer_->SetLayerTreeHost(nullptr);
+  if (proto.page_scale_layer_id() == Layer::INVALID_ID) {
+    page_scale_layer_ = nullptr;
+  } else {
+    DCHECK(layer_id_map_.find(proto.page_scale_layer_id()) !=
+           layer_id_map_.end());
+    page_scale_layer_ = layer_id_map_[proto.page_scale_layer_id()];
+  }
+  if (inner_viewport_scroll_layer_)
+    inner_viewport_scroll_layer_->SetLayerTreeHost(nullptr);
+  if (proto.inner_viewport_scroll_layer_id() == Layer::INVALID_ID) {
+    inner_viewport_scroll_layer_ = nullptr;
+  } else {
+    DCHECK(layer_id_map_.find(proto.inner_viewport_scroll_layer_id()) !=
+           layer_id_map_.end());
+    inner_viewport_scroll_layer_ =
+        layer_id_map_[proto.inner_viewport_scroll_layer_id()];
+  }
+  if (outer_viewport_scroll_layer_)
+    outer_viewport_scroll_layer_->SetLayerTreeHost(nullptr);
+  if (proto.outer_viewport_scroll_layer_id() == Layer::INVALID_ID) {
+    outer_viewport_scroll_layer_ = nullptr;
+  } else {
+    DCHECK(layer_id_map_.find(proto.outer_viewport_scroll_layer_id()) !=
+           layer_id_map_.end());
+    outer_viewport_scroll_layer_ =
+        layer_id_map_[proto.outer_viewport_scroll_layer_id()];
+  }
+
+  LayerSelectionFromProtobuf(&selection_, proto.selection());
+  property_trees_.FromProtobuf(proto.property_trees());
+  surface_id_namespace_ = proto.surface_id_namespace();
+  next_surface_sequence_ = proto.next_surface_sequence();
+}
+
 }  // namespace cc