Revert of Add builders for tracing event's structural arguments

cc/trees/single_thread_proxy.cc

Index: cc/trees/single_thread_proxy.cc
diff --git a/cc/trees/single_thread_proxy.cc b/cc/trees/single_thread_proxy.cc
index 2f67740db632d01f2d158708adf00ba2e1c2bff5..45dbe8984ada788b408195a2215cc26c82b873bd 100644
--- a/cc/trees/single_thread_proxy.cc
+++ b/cc/trees/single_thread_proxy.cc
@@ -369,15 +369,18 @@
   }
 }
 
-void SingleThreadProxy::AsValueInto(base::debug::TracedValue* state) const {
-  // The following line casts away const modifiers because it is just
-  // setting debug state. We still want the AsValue() function and its
-  // call chain to be const throughout.
-  DebugScopedSetImplThread impl(const_cast<SingleThreadProxy*>(this));
-
-  state->BeginDictionary("layer_tree_host_impl");
-  layer_tree_host_impl_->AsValueInto(state);
-  state->EndDictionary();
+scoped_ptr<base::Value> SingleThreadProxy::AsValue() const {
+  scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue());
+  {
+    // The following line casts away const modifiers because it is just
+    // setting debug state. We still want the AsValue() function and its
+    // call chain to be const throughout.
+    DebugScopedSetImplThread impl(const_cast<SingleThreadProxy*>(this));
+
+    state->Set("layer_tree_host_impl",
+               layer_tree_host_impl_->AsValue().release());
+  }
+  return state.PassAs<base::Value>();
 }
 
 void SingleThreadProxy::ForceSerializeOnSwapBuffers() {