LayerDebugInfo should not clobber trace output

ui/compositor/layer_unittest.cc

 // Copyright (c) 2012 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 "ui/compositor/layer.h"
 
 #include <stddef.h>
 
 #include <memory>
 #include <utility>
@@ skipping 2227 matching lines @@
 
   root->SetOpacity(0.5f);
   WaitForSwap();
   EXPECT_EQ(1u, animation_observer.animation_step_count());
 
   EXPECT_FALSE(animation_observer.shutdown());
   ResetCompositor();
   EXPECT_TRUE(animation_observer.shutdown());
 }
 
+TEST(LayerDebugInfoTest, LayerNameDoesNotClobber) {
+  Layer layer(LAYER_NOT_DRAWN);
+  layer.set_name("foo");
+  std::unique_ptr<base::trace_event::ConvertableToTraceFormat> debug_info =
+      layer.TakeDebugInfo(nullptr);
+  std::string trace_format("bar,");
+  debug_info->AppendAsTraceFormat(&trace_format);
+  std::string expected("bar,{\"layer_name\":\"foo\"}");
+  EXPECT_EQ(expected, trace_format);
+}
+
 }  // namespace ui