Launches a privileged utility process.

content/browser/child_process_launcher.h

 // Copyright (c) 2012 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 CONTENT_BROWSER_CHILD_PROCESS_LAUNCHER_H_
 #define CONTENT_BROWSER_CHILD_PROCESS_LAUNCHER_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "content/common/content_export.h"
 
 class CommandLine;
 
 namespace content {
 class SandboxedProcessLauncherDelegate;
 
 // Launches a process asynchronously and notifies the client of the process
 // handle when it's available.  It's used to avoid blocking the calling thread
 // on the OS since often it can take > 100 ms to create the process.
 class CONTENT_EXPORT ChildProcessLauncher {
  public:
+  // An interface for receiving callbacks with process-launching status.  Will
+  // be called on the thread that the ChildProcessLauncher was constructed on.
+  // Note that only OnProcessLaunched is required.
   class CONTENT_EXPORT Client {
    public:
-    // Will be called on the thread that the ChildProcessLauncher was
-    // constructed on.
+    // Called when the process is launched.
     virtual void OnProcessLaunched() = 0;
 
+    // Called if an error occurs launching the process.
+    virtual void OnProcessLaunchFailure() {};
+
    protected:
     virtual ~Client() {}
   };
 
   // Launches the process asynchronously, calling the client when the result is
   // ready.  Deleting this object before the process is created is safe, since
   // the callback won't be called.  If the process is still running by the time
   // this object destructs, it will be terminated.

[mef, 2014/01/17 16:57:06]

I think this comment is out of date, especially regards to cmd_line parameter.

[Drew Haven, 2014/01/22 23:14:25]

Right.  This is an interface now, so it doesn't take ownership of anything. I
moved this comment down to the static methods where it now belongs.

   // Takes ownership of cmd_line.
-  ChildProcessLauncher(
-#if defined(OS_WIN)
-      SandboxedProcessLauncherDelegate* delegate,
-#elif defined(OS_POSIX)
-      bool use_zygote,
-      const base::EnvironmentMap& environ,
-      int ipcfd,
-#endif
-      CommandLine* cmd_line,
-      int child_process_id,
-      Client* client);
-  ~ChildProcessLauncher();
+  ChildProcessLauncher() {};
+  virtual ~ChildProcessLauncher() {};
 
   // True if the process is being launched and so the handle isn't available.
-  bool IsStarting();
+  virtual bool IsStarting() = 0;
 
   // Getter for the process handle.  Only call after the process has started.
-  base::ProcessHandle GetHandle();
+  virtual base::ProcessHandle GetHandle() = 0;
 
   // Call this when the child process exits to know what happened to it.
   // |known_dead| can be true if we already know the process is dead as it can
   // help the implemention figure the proper TerminationStatus.
   // On Linux, the use of |known_dead| is subtle and can be crucial if an
   // accurate status is important. With |known_dead| set to false, a dead
   // process could be seen as running. With |known_dead| set to true, the
   // process will be killed if it was still running. See ZygoteHostImpl for
   // more discussion of Linux implementation details.
   // |exit_code| is the exit code of the process if it exited (e.g. status from
   // waitpid if on posix, from GetExitCodeProcess on Windows). |exit_code| may
   // be NULL.
-  base::TerminationStatus GetChildTerminationStatus(bool known_dead,
-                                                    int* exit_code);
+  virtual base::TerminationStatus GetChildTerminationStatus(bool known_dead,
+                                                            int* exit_code) = 0;
 
   // Changes whether the process runs in the background or not.  Only call
   // this after the process has started.
-  void SetProcessBackgrounded(bool background);
+  virtual void SetProcessBackgrounded(bool background) = 0;
 
   // Controls whether the child process should be terminated on browser
   // shutdown.
-  void SetTerminateChildOnShutdown(bool terminate_on_shutdown);
+  virtual void SetTerminateChildOnShutdown(bool terminate_on_shutdown) = 0;
+
+  // Create a standard ChildProcessLauncher.
+  static ChildProcessLauncher* Create(
+#if defined(OS_WIN)
+      SandboxedProcessLauncherDelegate* delegate,
+#elif defined(OS_POSIX)
+      bool use_zygote,
+      const base::EnvironmentMap& environ,
+      int ipcfd,
+#endif
+      CommandLine* cmd_line,
+      int child_process_id,
+      Client* client);
+
+#if defined(OS_WIN)
+  // Create a ChildProcessLauncher that attempts to create an elevated process.
+  static ChildProcessLauncher* CreateElevated(
+      CommandLine* cmd_line,
+      int child_process_id,
+      Client* client);
+#endif
 
  private:
-  class Context;
-
-  scoped_refptr<Context> context_;
-
   DISALLOW_COPY_AND_ASSIGN(ChildProcessLauncher);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_CHILD_PROCESS_LAUNCHER_H_