Enable startup tracing from command line flags in components/tracing

components/tracing/browser/trace_config_file.cc

Index: components/tracing/browser/trace_config_file.cc
diff --git a/components/tracing/browser/trace_config_file.cc b/components/tracing/browser/trace_config_file.cc
deleted file mode 100644
index 97f8a16810a8ad4e7b33416507acbffde1693d78..0000000000000000000000000000000000000000
--- a/components/tracing/browser/trace_config_file.cc
+++ /dev/null
@@ -1,147 +0,0 @@
-// Copyright (c) 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 "components/tracing/browser/trace_config_file.h"
-
-#include <stddef.h>
-
-#include <memory>
-#include <string>
-
-#include "base/command_line.h"
-#include "base/files/file_util.h"
-#include "base/json/json_reader.h"
-#include "base/logging.h"
-#include "base/memory/singleton.h"
-#include "base/values.h"
-#include "build/build_config.h"
-#include "components/tracing/common/tracing_switches.h"
-
-namespace tracing {
-
-namespace {
-
-// Maximum trace config file size that will be loaded, in bytes.
-const size_t kTraceConfigFileSizeLimit = 64 * 1024;
-
-// Trace config file path:
-// - Android: /data/local/chrome-trace-config.json
-// - Others: specified by --trace-config-file flag.
-#if defined(OS_ANDROID)
-const base::FilePath::CharType kAndroidTraceConfigFile[] =
-    FILE_PATH_LITERAL("/data/local/chrome-trace-config.json");
-#endif
-
-const base::FilePath::CharType kDefaultResultFile[] =
-    FILE_PATH_LITERAL("chrometrace.log");
-
-// String parameters that can be used to parse the trace config file content.
-const char kTraceConfigParam[] = "trace_config";
-const char kStartupDurationParam[] = "startup_duration";
-const char kResultFileParam[] = "result_file";
-
-} // namespace
-
-TraceConfigFile* TraceConfigFile::GetInstance() {
-  return base::Singleton<TraceConfigFile,
-                         base::DefaultSingletonTraits<TraceConfigFile>>::get();
-}
-
-TraceConfigFile::TraceConfigFile()
-    : is_enabled_(false),
-      trace_config_(base::trace_event::TraceConfig()),
-      startup_duration_(0),
-      result_file_(kDefaultResultFile) {
-#if defined(OS_ANDROID)
-  base::FilePath trace_config_file(kAndroidTraceConfigFile);
-#else
-  const base::CommandLine& command_line =
-      *base::CommandLine::ForCurrentProcess();
-  if (!command_line.HasSwitch(switches::kTraceConfigFile) ||
-      command_line.HasSwitch(switches::kTraceStartup) ||
-      command_line.HasSwitch(switches::kTraceShutdown)) {
-    return;
-  }
-  base::FilePath trace_config_file =
-      command_line.GetSwitchValuePath(switches::kTraceConfigFile);
-#endif
-
-  if (trace_config_file.empty()) {
-    // If the trace config file path is not specified, trace Chrome with the
-    // default configuration for 5 sec.
-    startup_duration_ = 5;
-    is_enabled_ = true;
-    DLOG(WARNING) << "Use default trace config.";
-    return;
-  }
-
-  if (!base::PathExists(trace_config_file)) {
-    DLOG(WARNING) << "The trace config file does not exist.";
-    return;
-  }
-
-  std::string trace_config_file_content;
-  if (!base::ReadFileToStringWithMaxSize(trace_config_file,
-                                         &trace_config_file_content,
-                                         kTraceConfigFileSizeLimit)) {
-    DLOG(WARNING) << "Cannot read the trace config file correctly.";
-    return;
-  }
-  is_enabled_ = ParseTraceConfigFileContent(trace_config_file_content);
-  if (!is_enabled_)
-    DLOG(WARNING) << "Cannot parse the trace config file correctly.";
-}
-
-TraceConfigFile::~TraceConfigFile() {
-}
-
-bool TraceConfigFile::ParseTraceConfigFileContent(const std::string& content) {
-  std::unique_ptr<base::Value> value(base::JSONReader::Read(content));
-  if (!value || !value->IsType(base::Value::Type::DICTIONARY))
-    return false;
-
-  std::unique_ptr<base::DictionaryValue> dict(
-      static_cast<base::DictionaryValue*>(value.release()));
-
-  base::DictionaryValue* trace_config_dict = NULL;
-  if (!dict->GetDictionary(kTraceConfigParam, &trace_config_dict))
-    return false;
-
-  trace_config_ = base::trace_event::TraceConfig(*trace_config_dict);
-
-  if (!dict->GetInteger(kStartupDurationParam, &startup_duration_))
-      startup_duration_ = 0;
-
-  if (startup_duration_ < 0)
-      startup_duration_ = 0;
-
-  base::FilePath::StringType result_file_str;
-  if (dict->GetString(kResultFileParam, &result_file_str))
-    result_file_ = base::FilePath(result_file_str);
-
-  return true;
-}
-
-bool TraceConfigFile::IsEnabled() const {
-  return is_enabled_;
-}
-
-base::trace_event::TraceConfig TraceConfigFile::GetTraceConfig() const {
-  DCHECK(IsEnabled());
-  return trace_config_;
-}
-
-int TraceConfigFile::GetStartupDuration() const {
-  DCHECK(IsEnabled());
-  return startup_duration_;
-}
-
-#if !defined(OS_ANDROID)
-base::FilePath TraceConfigFile::GetResultFile() const {
-  DCHECK(IsEnabled());
-  return result_file_;
-}
-#endif
-
-}  // namespace tracing