cc: Make LayerTreeImpl dump layer list to FrameViewer and Devtools

cc/trees/layer_tree_impl.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_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 422 matching lines @@
 }
 
 LayerListIterator<LayerImpl> LayerTreeImpl::begin() {
   return LayerListIterator<LayerImpl>(root_layer_);
 }
 
 LayerListIterator<LayerImpl> LayerTreeImpl::end() {
   return LayerListIterator<LayerImpl>(nullptr);
 }
 
+const LayerListIterator<LayerImpl> LayerTreeImpl::begin() const {
+  return LayerListIterator<LayerImpl>(root_layer_);
+}
+
+const LayerListIterator<LayerImpl> LayerTreeImpl::end() const {
+  return LayerListIterator<LayerImpl>(nullptr);
+}
+
 LayerListReverseIterator<LayerImpl> LayerTreeImpl::rbegin() {
   return LayerListReverseIterator<LayerImpl>(root_layer_);
 }
 
 LayerListReverseIterator<LayerImpl> LayerTreeImpl::rend() {
   return LayerListReverseIterator<LayerImpl>(nullptr);
 }
 
 void LayerTreeImpl::AddToElementMap(LayerImpl* layer) {
   if (!layer->element_id() || !layer->mutable_properties())
@@ skipping 807 matching lines @@
       continue;
     LayerImpl* layer_impl = *it;
     layer_impl->GetAllPrioritizedTilesForTracing(prioritized_tiles);
   }
 }
 
 void LayerTreeImpl::AsValueInto(base::trace_event::TracedValue* state) const {
   TracedValue::MakeDictIntoImplicitSnapshot(state, "cc::LayerTreeImpl", this);
   state->SetInteger("source_frame_number", source_frame_number_);
 
-  state->BeginDictionary("root_layer");
-  root_layer_->AsValueInto(state);
-  state->EndDictionary();
-
   state->BeginArray("render_surface_layer_list");
   LayerIterator end = LayerIterator::End(&render_surface_layer_list_);
   for (LayerIterator it = LayerIterator::Begin(&render_surface_layer_list_);
        it != end; ++it) {
     if (!it.represents_itself())
       continue;
     TracedValue::AppendIDRef(*it, state);
   }
   state->EndArray();
 
   state->BeginArray("swap_promise_trace_ids");
   for (const auto& swap_promise : swap_promise_list_)
     state->AppendDouble(swap_promise->TraceId());
   state->EndArray();
 
   state->BeginArray("pinned_swap_promise_trace_ids");
   for (const auto& swap_promise : pinned_swap_promise_list_)
     state->AppendDouble(swap_promise->TraceId());
   state->EndArray();
+
+  state->BeginArray("layers");
+  for (auto* layer : *this) {
+    state->BeginDictionary();
+    layer->AsValueInto(state);
+    state->EndDictionary();
+  }
+  state->EndArray();
 }
 
 bool LayerTreeImpl::DistributeRootScrollOffset(
     const gfx::ScrollOffset& root_offset) {
   if (!InnerViewportScrollLayer())
     return false;
 
   DCHECK(OuterViewportScrollLayer());
 
   // If we get here, we have both inner/outer viewports, and need to distribute
@@ skipping 786 matching lines @@
 }
 
 void LayerTreeImpl::ResetAllChangeTracking(PropertyTrees::ResetFlags flag) {
   layers_that_should_push_properties_.clear();
   for (auto* layer : *this)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking(flag);
 }
 
 }  // namespace cc