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// 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.
#ifndef COMPONENTS_TRACING_BROWSER_TRACE_CONFIG_FILE_H_
#define COMPONENTS_TRACING_BROWSER_TRACE_CONFIG_FILE_H_
#include "base/files/file_path.h"
#include "base/macros.h"
#include "base/trace_event/trace_config.h"
#include "build/build_config.h"
#include "components/tracing/tracing_export.h"
namespace base {
template <typename Type> struct DefaultSingletonTraits;
} // namespace base
namespace tracing {
// TraceConfigFile is a singleton that contains the configurations of tracing.
// One can create a trace config file and use it to configure startup and/or
// shutdown tracing.
//
// The trace config file should be JSON formated. One example is:
// {
// "trace_config": {
// "record_mode": "record-until-full",
// "included_categories": ["cc", "skia"]
// },
// "startup_duration": 5,
// "result_file": "chrometrace.log"
// }
//
// trace_config: The configuration of tracing. Please see the details in
// base/trace_event/trace_config.h.
//
// startup_duration: The duration for startup tracing in terms of seconds.
// Tracing will stop automatically after the duration. If this
// value is not specified, the duration is 0 and one needs
// to stop tracing by other ways, e.g., by DevTools, or get
// the result file after shutting the browser down.
//
// result_file: The file that contains the trace log. The default result
// file path is chrometrace.log. Chrome will dump the trace
// log to this file
// 1) after startup_duration if it is specified;
// 2) or after browser shutdown if startup duration is 0.
// One can also stop tracing and get the result by other ways,
// e.g., by DevTools. In that case, the trace log will not be
// saved to this file.
// Notice: This is not supported on Android. The result file
// path will be generated by tracing controller.
//
// The trace config file can be specified by the --trace-config-file flag on
// most platforms except on Android, e.g., --trace-config-file=path/to/file/.
// This flag should not be used with --trace-startup or --trace-shutdown. If
// those two flags are used, --trace-config-file flag will be ignored. If the
// --trace-config-file flag is used without the file path, Chrome will do
// startup tracing with 5 seconds' startup duration.
//
// On Android, Chrome does not read the --trace-config-file flag, because not
// all Chrome based browsers read customized flag, e.g., Android WebView. Chrome
// on Android reads from a fixed file location:
// /data/local/chrome-trace-config.json
// If this file exists, Chrome will start tracing according to the configuration
// specified in the file, otherwise, Chrome will not start tracing.
class TRACING_EXPORT TraceConfigFile {
public:
static TraceConfigFile* GetInstance();
bool IsEnabled() const;
base::trace_event::TraceConfig GetTraceConfig() const;
int GetStartupDuration() const;
#if !defined(OS_ANDROID)
base::FilePath GetResultFile() const;
#endif
private:
// This allows constructor and destructor to be private and usable only
// by the Singleton class.
friend struct base::DefaultSingletonTraits<TraceConfigFile>;
TraceConfigFile();
~TraceConfigFile();
bool ParseTraceConfigFileContent(const std::string& content);
bool is_enabled_;
base::trace_event::TraceConfig trace_config_;
int startup_duration_;
base::FilePath result_file_;
DISALLOW_COPY_AND_ASSIGN(TraceConfigFile);
};
} // namespace tracing
#endif // COMPONENTS_TRACING_BROWSER_TRACE_CONFIG_FILE_H_
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