Adds a command-line flag indicating an open and listening socket to

headless/public/headless_browser.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 HEADLESS_PUBLIC_HEADLESS_BROWSER_H_
 #define HEADLESS_PUBLIC_HEADLESS_BROWSER_H_
 
 #include <memory>
 #include <string>
 #include <unordered_map>
@@ skipping 90 matching lines @@
   Options(Options&& options);
   ~Options();
 
   Options& operator=(Options&& options);
 
   // Command line options to be passed to browser.
   int argc;
   const char** argv;
 
   // Address at which DevTools should listen for connections. Disabled by
-  // default.
+  // default. Mutually exclusive with devtools_socket_fd.
   net::IPEndPoint devtools_endpoint;
 
+  // The fd of an already-open socket inherited from a parent process. Disabled
+  // by default. Mutually exclusive with devtools_endpoint.
+  size_t devtools_socket_fd;
+
+  // A single way to test whether the devtools server has been requested.
+  bool DevtoolsServerEnabled();
+
   // Optional message pump that overrides the default. Must outlive the browser.
   base::MessagePump* message_pump;
 
   // Run the browser in single process mode instead of using separate renderer
   // processes as per default. Note that this also disables any sandboxing of
   // web content, which can be a security risk.
   bool single_process_mode;
 
   // Run the browser without renderer sandbox. This option can be
   // a security risk and should be used with caution.
@@ skipping 56 matching lines @@
 
 class HeadlessBrowser::Options::Builder {
  public:
   Builder(int argc, const char** argv);
   Builder();
   ~Builder();
 
   // Browser-wide settings.
 
   Builder& EnableDevToolsServer(const net::IPEndPoint& endpoint);
+  Builder& EnableDevToolsServer(const size_t socket_fd);
   Builder& SetMessagePump(base::MessagePump* message_pump);
   Builder& SetSingleProcessMode(bool single_process_mode);
   Builder& SetDisableSandbox(bool disable_sandbox);
   Builder& SetGLImplementation(const std::string& gl_implementation);
   Builder& AddMojoServiceName(const std::string& mojo_service_name);
 
   // Per-context settings.
 
   Builder& SetProductNameAndVersion(
       const std::string& product_name_and_version);
@@ skipping 43 matching lines @@
 // the main loop, it will only return after HeadlessBrowser::Shutdown() is
 // called, returning the exit code for the process. It is not possible to
 // initialize the browser again after it has been torn down.
 int HeadlessBrowserMain(
     HeadlessBrowser::Options options,
     const base::Callback<void(HeadlessBrowser*)>& on_browser_start_callback);
 
 }  // namespace headless
 
 #endif  // HEADLESS_PUBLIC_HEADLESS_BROWSER_H_