Revert of Remove blink::WebLayerClient and WebGraphicsLayerDebugInfo.

cc/blink/web_layer_impl.cc

Index: cc/blink/web_layer_impl.cc
diff --git a/cc/blink/web_layer_impl.cc b/cc/blink/web_layer_impl.cc
index bde0bdf1925251f036aeeaffef70051c76fdd42e..726cfa6c060f25277b93c740ce9c3ae69dc2ec66 100644
--- a/cc/blink/web_layer_impl.cc
+++ b/cc/blink/web_layer_impl.cc
@@ -25,6 +25,8 @@
 #include "cc/trees/layer_tree_host.h"
 #include "third_party/WebKit/public/platform/WebFloatPoint.h"
 #include "third_party/WebKit/public/platform/WebFloatRect.h"
+#include "third_party/WebKit/public/platform/WebGraphicsLayerDebugInfo.h"
+#include "third_party/WebKit/public/platform/WebLayerClient.h"
 #include "third_party/WebKit/public/platform/WebLayerPositionConstraint.h"
 #include "third_party/WebKit/public/platform/WebLayerScrollClient.h"
 #include "third_party/WebKit/public/platform/WebSize.h"
@@ -52,15 +54,20 @@
 
 WebLayerImpl::WebLayerImpl()
     : layer_(Layer::Create(LayerSettings())), contents_opaque_is_fixed_(false) {
+  web_layer_client_ = nullptr;
+  layer_->SetLayerClient(this);
 }
 
 WebLayerImpl::WebLayerImpl(scoped_refptr<Layer> layer)
     : layer_(layer), contents_opaque_is_fixed_(false) {
+  web_layer_client_ = nullptr;
+  layer_->SetLayerClient(this);
 }
 
 WebLayerImpl::~WebLayerImpl() {
   if (animation_delegate_adapter_.get())
     layer_->set_layer_animation_delegate(nullptr);
+  web_layer_client_ = nullptr;
   layer_->SetLayerClient(nullptr);
 }
 
@@ -486,12 +493,39 @@
   return !layer_->layer_tree_host();
 }
 
-void WebLayerImpl::setLayerClient(cc::LayerClient* client) {
-  layer_->SetLayerClient(client);
-}
-
-const cc::Layer* WebLayerImpl::ccLayer() const {
-  return layer_.get();
+void WebLayerImpl::setWebLayerClient(blink::WebLayerClient* client) {
+  web_layer_client_ = client;
+}
+
+class TracedDebugInfo : public base::trace_event::ConvertableToTraceFormat {
+ public:
+  // This object takes ownership of the debug_info object.
+  explicit TracedDebugInfo(blink::WebGraphicsLayerDebugInfo* debug_info)
+      : debug_info_(debug_info) {}
+  void AppendAsTraceFormat(std::string* out) const override {
+    DCHECK(thread_checker_.CalledOnValidThread());
+    blink::WebString web_string;
+    debug_info_->appendAsTraceFormat(&web_string);
+    out->append(web_string.utf8());
+  }
+
+ private:
+  ~TracedDebugInfo() override {}
+  scoped_ptr<blink::WebGraphicsLayerDebugInfo> debug_info_;
+  base::ThreadChecker thread_checker_;
+};
+
+scoped_refptr<base::trace_event::ConvertableToTraceFormat>
+WebLayerImpl::TakeDebugInfo() {
+  if (!web_layer_client_)
+    return nullptr;
+  blink::WebGraphicsLayerDebugInfo* debug_info =
+      web_layer_client_->takeDebugInfoFor(this);
+
+  if (debug_info)
+    return new TracedDebugInfo(debug_info);
+  else
+    return nullptr;
 }
 
 void WebLayerImpl::setScrollParent(blink::WebLayer* parent) {