Chromium入坑之旅：chromium启动流程

Chromium版本：84.0.4113.0

一、入口

\src\chrome\app\chrome_exe_main_win.cc 源文件行：175

#if !defined(WIN_CONSOLE_APP)
int APIENTRY wWinMain(HINSTANCE instance, HINSTANCE prev, wchar_t*, int) {
   
#else
int main() {
   
  HINSTANCE instance = GetModuleHandle(nullptr);
#endif
  install_static::InitializeFromPrimaryModule();
  SignalInitializeCrashReporting();

  // Done here to ensure that OOMs that happen early in process initialization
  // are correctly signaled to the OS.
  base::EnableTerminationOnOutOfMemory();

  // Initialize the CommandLine singleton from the environment.
  base::CommandLine::Init(0, nullptr);
  const base::CommandLine* command_line =
      base::CommandLine::ForCurrentProcess();

  const std::string process_type =
      command_line->GetSwitchValueASCII(switches::kProcessType);

  // Confirm that an explicit prefetch profile is used for all process types
  // except for the browser process. Any new process type will have to assign
  // itself a prefetch id. See kPrefetchArgument* constants in
  // content_switches.cc for details.
  DCHECK(process_type.empty() ||
         HasValidWindowsPrefetchArgument(*command_line));

  if (process_type == crash_reporter::switches::kCrashpadHandler) {
   
    // Check if we should monitor the exit code of this process
    std::unique_ptr<browser_watcher::ExitCodeWatcher> exit_code_watcher;

    crash_reporter::SetupFallbackCrashHandling(*command_line);
    // no-periodic-tasks is specified for self monitoring crashpad instances.
    // This is to ensure we are a crashpad process monitoring the browser
    // process and not another crashpad process.
    if (!command_line->HasSwitch("no-periodic-tasks")) {
   
      // Retrieve the client process from the command line
      crashpad::InitialClientData initial_client_data;
      if (initial_client_data.InitializeFromString(
              command_line->GetSwitchValueASCII("initial-client-data"))) {
   
        // Setup exit code watcher to monitor the parent process
        HANDLE duplicate_handle = INVALID_HANDLE_VALUE;
        if (DuplicateHandle(
                ::GetCurrentProcess(), initial_client_data.client_process(),
                ::GetCurrentProcess(), &duplicate_handle,
                PROCESS_QUERY_INFORMATION, FALSE, DUPLICATE_SAME_ACCESS)) {
   
          base::Process parent_process(duplicate_handle);
          exit_code_watcher =
              std::make_unique<browser_watcher::ExitCodeWatcher>();
          if (exit_code_watcher->Initialize(std::move(parent_process))) {
   
            exit_code_watcher->StartWatching();
          }
        }
      }
    }

    // The handler process must always be passed the user data dir on the
    // command line.
    DCHECK(command_line->HasSwitch(switches::kUserDataDir));

    base::FilePath user_data_dir =
        command_line->GetSwitchValuePath(switches::kUserDataDir);
    int crashpad_status = crash_reporter::RunAsCrashpadHandler(
        *base::CommandLine::ForCurrentProcess(), user_data_dir,
        switches::kProcessType, switches::kUserDataDir);
    if (crashpad_status != 0 && exit_code_watcher) {
   
      // Crashpad failed to initialize, explicitly stop the exit code watcher
      // so the crashpad-handler process can exit with an error
      exit_code_watcher->StopWatching();
    }
    return crashpad_status;
  } else if (process_type == crash_reporter::switches::kFallbackCrashHandler) {
   
    return RunFallbackCrashHandler(*command_line);
  }

  const base::TimeTicks exe_entry_point_ticks = base::TimeTicks::Now();

  // Signal Chrome Elf that Chrome has begun to start.
  SignalChromeElf();

  // The exit manager is in charge of calling the dtors of singletons.
  base::AtExitManager exit_manager;

  // Only enable High DPI support for browser and GPU process.
  if (process_type.empty() || process_type == switches::kGpuProcess)
    base::win::EnableHighDPISupport();

  if (AttemptFastNotify