Remove ui.tracing

This feature is redundant with the Timeline in dart:developer. I've already
switched all the clients over to using dart:developer.

sky/engine/bindings/dart_ui.cc

@@ -7,7 +7,6 @@
 #include "gen/sky/bindings/DartGlobal.h"
 #include "sky/engine/bindings/dart_runtime_hooks.h"
 #include "sky/engine/core/painting/painting.h"
-#include "sky/engine/core/tracing/tracing.h"
 #include "sky/engine/core/window/window.h"
 #include "sky/engine/tonic/dart_converter.h"
 #include "sky/engine/tonic/dart_error.h"
@@ -41,7 +40,6 @@ void DartUI::InitForIsolate() {
     DartRuntimeHooks::RegisterNatives(g_natives);
     Window::RegisterNatives(g_natives);
     Painting::RegisterNatives(g_natives);
-    Tracing::RegisterNatives(g_natives);
   }
 
   DART_CHECK_VALID(Dart_SetNativeResolver(

sky/engine/core/core.gni

@@ -231,8 +231,6 @@ sky_core_files = [
   "text/Paragraph.h",
   "text/ParagraphBuilder.cpp",
   "text/ParagraphBuilder.h",
-  "tracing/tracing.cc",
-  "tracing/tracing.h",
   "window/window.cc",
   "window/window.h",
 ]
@@ -265,7 +263,6 @@ core_dart_files = get_path_info([
                                   "dart/lerp.dart",
                                   "dart/painting.dart",
                                   "dart/text.dart",
-                                  "dart/tracing.dart",
                                   "dart/window.dart",
                                   "painting/Color.dart",
                                   "painting/ColorFilter.dart",

sky/engine/core/dart/tracing.dart

-// 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.
-
-part of dart_ui;
-
-class _Tracing {
-  void begin(String name) native "Tracing_begin";
-  void end(String name) native "Tracing_end";
-}
-
-final _Tracing tracing = new _Tracing();

sky/engine/core/tracing/tracing.cc

-// 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.
-
-#include "sky/engine/core/tracing/tracing.h"
-
-#include "base/trace_event/trace_event.h"
-#include "sky/engine/tonic/dart_converter.h"
-#include "sky/engine/wtf/text/StringUTF8Adaptor.h"
-
-namespace blink {
-
-namespace {
-
-void BeginTracing(Dart_NativeArguments args) {
-  Dart_Handle exception = nullptr;
-  String name = DartConverter<String>::FromArguments(args, 1, exception);
-  if (exception) {
-    Dart_ThrowException(exception);
-    return;
-  }
-
-  StringUTF8Adaptor utf8(name);
-  // TRACE_EVENT_COPY_BEGIN0 needs a c-style null-terminated string.
-  CString cstring(utf8.data(), utf8.length());
-  TRACE_EVENT_COPY_BEGIN0("script", cstring.data());
-}
-
-void EndTracing(Dart_NativeArguments args) {
-  Dart_Handle exception = nullptr;
-  String name = DartConverter<String>::FromArguments(args, 1, exception);
-  if (exception) {
-    Dart_ThrowException(exception);
-    return;
-  }
-
-  StringUTF8Adaptor utf8(name);
-  // TRACE_EVENT_COPY_END0 needs a c-style null-terminated string.
-  CString cstring(utf8.data(), utf8.length());
-  TRACE_EVENT_COPY_END0("script", cstring.data());
-}
-
-}  // namespace
-
-void Tracing::RegisterNatives(DartLibraryNatives* natives) {
-  natives->Register({
-    { "Tracing_begin", BeginTracing, 2, true },
-    { "Tracing_end", EndTracing, 2, true },
-  });
-}
-
-}  // namespace blink

sky/engine/core/tracing/tracing.h

-// 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.
-
-#ifndef SKY_ENGINE_CORE_TRACING_TRACING_H_
-#define SKY_ENGINE_CORE_TRACING_TRACING_H_
-
-#include "sky/engine/tonic/dart_library_natives.h"
-
-namespace blink {
-
-class Tracing {
- public:
-   static void RegisterNatives(DartLibraryNatives* natives);
-};
-
-}  // namespace blink
-
-#endif  // SKY_ENGINE_CORE_TRACING_TRACING_H_