Dart: Remove unused library and example

mojo/common/dart/lib/tracing_helper.dart

Index: mojo/common/dart/lib/tracing_helper.dart
diff --git a/mojo/common/dart/lib/tracing_helper.dart b/mojo/common/dart/lib/tracing_helper.dart
deleted file mode 100644
index d48a3a409a8573537644e7a4fe7348e2354e5d81..0000000000000000000000000000000000000000
--- a/mojo/common/dart/lib/tracing_helper.dart
+++ /dev/null
@@ -1,186 +0,0 @@
-// 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.
-
-library tracing;
-
-import 'dart:async';
-import 'dart:collection';
-import 'dart:convert';
-import 'dart:core';
-import 'dart:io';
-import 'dart:isolate';
-
-import 'package:common/src/trace_provider_impl.dart';
-export 'package:common/src/trace_provider_impl.dart' show TraceSendTiming;
-
-import 'package:mojo/application.dart';
-import 'package:mojo/core.dart';
-import 'package:mojo_services/tracing/tracing.mojom.dart';
-
-// Phases indicating the nature of the event in the trace log.
-// These should be in sync with definitions in
-// //base/trace_event/trace_event.h
-const traceEventInstant = "I";
-const traceEventPhaseBegin = "B";
-const traceEventPhaseEnd = "E";
-const traceEventPhaseAsyncBegin = "S";
-const traceEventPhaseAsyncEnd = "F";
-const traceEventDuration = "X";
-
-// TracingHelper is used by Dart code running in the Mojo shell in order
-// to perform tracing.
-class TracingHelper {
-  TraceProviderImpl _impl;
-  int _tid;
-  static TracingHelper _tracing;
-  // Construct an instance of TracingHelper from within your application's
-  // |initialize()| method. |appName| will be used to form a thread identifier
-  // for use in trace messages. If |appName| is longer than 20 characters then
-  // only the last 20 characters of |appName| will be used.
-  TracingHelper.fromApplication(Application app, String appName,
-      [TraceSendTiming timing = TraceSendTiming.IMMEDIATE]) {
-    // Masked because the tid is expected to be a 32-bit int.
-    _tid = [appName, Isolate.current]
-            .fold(7, (hash, element) => 31 * hash + element.hashCode) &
-        0x7fffffff;
-    _impl = new TraceProviderImpl(timing);
-    ApplicationConnection connection = app.connectToApplication("mojo:tracing");
-    connection.provideService(TraceProviderName, (e) {
-      _impl.connect(e);
-    });
-    assert(_tracing == null);
-    _tracing = this;
-  }
-
-  // Factory to return the singleton instance of the TracingHelper. The isolate
-  // must have constructed the object using TracingHelper.fromApplication
-  // atleast once before using this factory.
-  factory TracingHelper() {
-    assert(_tracing != null);
-    return _tracing;
-  }
-
-  bool isActive() {
-    return (_impl != null) && _impl.isActive();
-  }
-
-  // Invoke this at the beginning of a synchronous function whose
-  // duration you wish to trace. Invoke |end()| on the returned object.
-  FunctionTrace begin(String functionName, String categories,
-      {Map<String, String> args}) {
-    return _beginFunction(functionName, categories, traceEventPhaseBegin,
-        args: args);
-  }
-
-  // Invoke this right before an asynchronous function whose duration
-  // you wish to trace. Invoke |end()| on the returned object.
-  FunctionTrace beginAsync(String functionName, String categories,
-      {Map<String, String> args}) {
-    return _beginFunction(functionName, categories, traceEventPhaseAsyncBegin,
-        args: args);
-  }
-
-  void traceInstant(String name, String categories,
-      {Map<String, String> args}) {
-    _sendTraceMessage(name, categories, traceEventInstant, 0, args: args);
-  }
-
-  void traceDuration(String name, String categories, int start, int end,
-      {Map<String, String> args}) {
-    _sendTraceMessage(name, categories, traceEventDuration, 0,
-        args: args, start: start, duration: end - start);
-  }
-
-  FunctionTrace _beginFunction(
-      String functionName, String categories, String phase,
-      {Map<String, String> args}) {
-    assert(functionName != null);
-    final trace = new _FunctionTraceImpl(
-        this, isActive() ? functionName : null, categories, phase);
-    _sendTraceMessage(functionName, categories, phase, trace.hashCode,
-        args: args);
-    return trace;
-  }
-
-  void _endFunction(
-      String functionName, String categories, String phase, int traceId) {
-    _sendTraceMessage(functionName, categories, phase, traceId);
-  }
-
-  void _sendTraceMessage(
-      String name, String categories, String phase, int traceId,
-      {Map<String, String> args, int start, int duration}) {
-    if (isActive()) {
-      var time = (start != null) ? start : getTimeTicksNow();
-      var map = new HashMap();
-      map["name"] = name;
-      map["cat"] = categories;
-      map["ph"] = phase;
-      map["ts"] = time;
-      map["pid"] = pid;
-      map["tid"] = _tid;
-      map["id"] = traceId;
-      if (duration != null) {
-        map["dur"] = duration;
-      }
-      if (args != null) {
-        map["args"] = args;
-      }
-      _impl.sendTraceMessage(JSON.encode(map));
-    }
-  }
-
-  // A convenience method that wraps a closure in a begin-end pair of
-  // tracing calls.
-  dynamic trace(String functionName, String categories, closure(),
-      {Map<String, String> args}) {
-    FunctionTrace ft = begin(functionName, categories, args: args);
-    final returnValue = closure();
-    ft.end();
-    return returnValue;
-  }
-
-  // A convenience method that wraps a closure in a begin-end pair of
-  // async tracing calls. The return value should either be returned or awaited.
-  Future traceAsync(String functionName, String categories, Future closure(),
-      {Map<String, String> args}) {
-    FunctionTrace ft = beginAsync(functionName, categories, args: args);
-    final Future returnValue = closure();
-    returnValue.whenComplete(ft.end);
-    return returnValue;
-  }
-}
-
-// An instance of FunctionTrace is returned from |begin()|, |beginAsync()|.
-// Invoke |end()| to end the trace from every exit point in the function you are
-// tracing.
-abstract class FunctionTrace {
-  void end();
-}
-
-class _FunctionTraceImpl implements FunctionTrace {
-  TracingHelper _tracing;
-  String _functionName;
-  String _categories;
-  String _beginPhase;
-
-  _FunctionTraceImpl(
-      this._tracing, this._functionName, this._categories, this._beginPhase) {
-    assert(_beginPhase == traceEventPhaseBegin ||
-        _beginPhase == traceEventPhaseAsyncBegin);
-  }
-
-  @override
-  void end() {
-    if (_functionName != null) {
-      if (_beginPhase == traceEventPhaseBegin) {
-        _tracing._endFunction(
-            _functionName, _categories, traceEventPhaseEnd, hashCode);
-      } else if (_beginPhase == traceEventPhaseAsyncBegin) {
-        _tracing._endFunction(
-            _functionName, _categories, traceEventPhaseAsyncEnd, hashCode);
-      }
-    }
-  }
-}