Add support for (de)serializing LayerTreeHost.

cc/proto/layer_tree_host.proto

Index: cc/proto/layer_tree_host.proto
diff --git a/cc/proto/layer_tree_host.proto b/cc/proto/layer_tree_host.proto
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index 0000000000000000000000000000000000000000..1481d840326948ddce98dd961be2b95793017e8c
--- /dev/null
+++ b/cc/proto/layer_tree_host.proto
@@ -0,0 +1,123 @@
+// Copyright 2015 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.
+
+syntax = "proto2";
+
+import "layer.proto";
+import "layer_selection_bound.proto";
+import "layer_tree_settings.proto";
+import "layer_tree_debug_state.proto";
+import "property_tree.proto";
+import "size.proto";
+import "vector2df.proto";
+
+package cc.proto;
+
+option optimize_for = LITE_RUNTIME;
+
+message LayerTreeHost {
+  // struct UIResourceClientData {
+  //  UIResourceClient* client;
+  //  gfx::Size size;
+  //};
+
+  // typedef base::hash_map<UIResourceId, UIResourceClientData>
+  //    UIResourceClientMap;
+  // UIResourceClientMap ui_resource_client_map_;
+  // int next_ui_resource_id_;
+
+  // typedef std::vector<UIResourceRequest> UIResourceRequestQueue;
+  // UIResourceRequestQueue ui_resource_request_queue_;
+
+  optional bool needs_full_tree_sync = 1;
+  optional bool needs_meta_info_recomputation = 2;
+
+  // LayerTreeHostClient* client_;

[vmpstr, 2015/12/18 19:15:13]

These are created on the client side independently right?

[nyquist, 2016/01/11 20:05:35]

Yes.

+  // scoped_ptr<Proxy> proxy_;
+  // scoped_ptr<TaskRunnerProvider> task_runner_provider_;
+
+  optional int32 source_frame_number = 3;
+  optional int32 meta_information_sequence_number = 4;
+  // for logging, so skip for now
+  // scoped_ptr<RenderingStatsInstrumentation> rendering_stats_instrumentation_;
+
+  // scoped_ptr<OutputSurface> new_output_surface_;

[vmpstr, 2015/12/18 19:15:13]

The server shouldn't have these, right?

[nyquist, 2016/01/11 20:05:35]

Yeah, the output surface should only be on the client.

+  // scoped_ptr<OutputSurface> current_output_surface_;
+  // bool output_surface_lost_;
+
+  optional LayerNode root_layer = 5;
+  optional LayerUpdate layer_updates = 6;
+  // LayerNode

[vmpstr, 2015/12/18 19:15:13]

What are these?

[nyquist, 2016/01/11 20:05:35]

Just comments about what the proto message names are.

+  // LayerUpdate
+
+  optional LayerNode hud_layer = 7;
+  optional LayerUpdate hud_layer_updates = 8;
+  // LayerNode
+  // LayerUpdate
+
+  // base::WeakPtr<InputHandler> input_handler_weak_ptr_;
+
+  optional LayerTreeSettings settings = 9;
+  // kind of together with hud layer things
+  optional LayerTreeDebugState debug_state = 10;
+  optional Size device_viewport_size = 11;
+  optional bool top_controls_shrink_blink_size = 12;
+  optional float top_controls_height = 13;
+  optional float top_controls_shown_ratio = 14;
+  optional float device_scale_factor = 15;
+  optional float painted_device_scale_factor = 16;
+
+  // don't really need this, so skip. we'll handle this on the client.
+  // bool visible_;

[vmpstr, 2015/12/18 19:15:13]

I'd want to verify if this is possible to switch from the server side

[nyquist, 2016/01/11 20:05:35]

This will be sent separately from the client to the engine, but will basically
be controlled by the client.

+
+  optional float page_scale_factor = 17;
+  optional float min_page_scale_factor = 18;
+  optional float max_page_scale_factor = 19;
+  optional Vector2dF elastic_overscroll = 20;
+  optional bool has_gpu_rasterization_trigger = 21;
+  optional bool content_is_suitable_for_gpu_rasterization = 22;
+  optional bool gpu_rasterization_histogram_recorded = 23;

[vmpstr, 2015/12/18 19:15:13]

This is a bit awkward to serialize. Either the client shouldn't care or the
server shouldn't have the right value.

[nyquist, 2016/01/11 20:05:35]

Agreed. I'll remove it.

+
+  optional uint32 background_color = 24; /* SkColor */
+  optional bool has_transparent_background = 25;
+
+  // skip animations for now

[vmpstr, 2015/12/18 19:15:13]

This looks iffy. Why do we skip animations?

[nyquist, 2016/01/11 20:05:35]

We don't know how to serialize animations yet. :-(

+  // scoped_ptr<AnimationRegistrar> animation_registrar_;
+  // scoped_ptr<AnimationHost> animation_host_;
+
+  // scoped_ptr<PendingPageScaleAnimation> pending_page_scale_animation_;
+
+  // If set, then page scale animation has completed, but the client hasn't been
+  // notified about it yet.
+  // bool did_complete_scale_animation_;
+
+  optional bool in_paint_layer_contents = 26;
+
+  optional int32 id = 27;
+  optional bool next_commit_forces_redraw = 28;
+
+  optional int32 overscroll_elasticity_layer_id = 29;
+  optional int32 page_scale_layer = 30;
+  optional int32 inner_viewport_scroll_layer = 31;
+  optional int32 outer_viewport_scroll_layer = 32;
+
+  optional LayerSelection selection = 33;
+
+  // SharedBitmapManager* shared_bitmap_manager_;
+  // gpu::GpuMemoryBufferManager* gpu_memory_buffer_manager_;
+  // TaskGraphRunner* task_graph_runner_;
+
+  // promise to ignore it for now.

[vmpstr, 2015/12/18 19:15:13]

:P what is this used for?

[nyquist, 2016/01/11 20:05:35]

perf measurements apparently.

+  // std::vector<scoped_ptr<SwapPromise>> swap_promise_list_;
+  // std::set<SwapPromiseMonitor*> swap_promise_monitor_;
+
+  optional PropertyTrees property_trees = 34;
+
+  // part of the root layer and layer updates
+  // typedef base::hash_map<int, Layer*> LayerIdMap;
+  // LayerIdMap layer_id_map_;
+
+  optional uint32 surface_id_namespace = 35;
+  optional uint32 next_surface_sequence = 36;
+}