Simplify ChildProcessLauncher

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/files/scoped_file.h"
+#include "base/memory/weak_ptr.h"
 #include "base/process/kill.h"
 #include "base/process/launch.h"
 #include "base/process/process.h"
+#include "base/threading/non_thread_safe.h"
 #include "content/common/content_export.h"
+#include "content/public/browser/browser_thread.h"
 
 namespace base {
 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 {
+class CONTENT_EXPORT ChildProcessLauncher : public base::NonThreadSafe {
  public:
   class CONTENT_EXPORT Client {
    public:
     // Will be called on the thread that the ChildProcessLauncher was
     // constructed on.
     virtual void OnProcessLaunched() = 0;
 
     virtual void OnProcessLaunchFailed() {};
 
    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.
   // Takes ownership of cmd_line.
   ChildProcessLauncher(
       SandboxedProcessLauncherDelegate* delegate,
       base::CommandLine* cmd_line,
       int child_process_id,
-      Client* client);
+      Client* client,
+      bool terminate_on_shutdown);
   ~ChildProcessLauncher();
 
   // True if the process is being launched and so the handle isn't available.
   bool IsStarting();
 
   // Getter for the process.  Only call after the process has started.
   const base::Process& GetProcess() const;
 
   // 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);
 
   // Changes whether the process runs in the background or not.  Only call
   // this after the process has started.
   void SetProcessBackgrounded(bool background);
 
-  // Controls whether the child process should be terminated on browser
-  // shutdown.
-  void SetTerminateChildOnShutdown(bool terminate_on_shutdown);
-
   // Replaces the ChildProcessLauncher::Client for testing purposes. Returns the
   // previous  client.
   Client* ReplaceClientForTest(Client* client);
 
  private:
-  class Context;
+  // Posts a task to the launcher thread to do the actual work.
+  void Launch(SandboxedProcessLauncherDelegate* delegate,
+              base::CommandLine* cmd_line,
+              int child_process_id);
 
-  scoped_refptr<Context> context_;
+  void UpdateTerminationStatus(bool known_dead);
+
+  // This is always called on the client thread after an attempt
+  // to launch the child process on the launcher thread.
+  // It makes sure we always perform the necessary cleanup if the
+  // client went away.
+  static void DidLaunch(base::WeakPtr<ChildProcessLauncher> instance,
+                        bool terminate_on_shutdown,
+                        bool zygote,
+#if defined(OS_ANDROID)
+                        base::ScopedFD ipcfd,
+#endif
+                        base::Process process);
+
+  // Notifies the client about the result of the operation.
+  void Notify(bool zygote,
+#if defined(OS_ANDROID)
+              base::ScopedFD ipcfd,
+#endif
+              base::Process process);
+
+  Client* client_;
+  BrowserThread::ID client_thread_id_;
+  base::Process process_;
+  base::TerminationStatus termination_status_;
+  int exit_code_;
+  bool zygote_;
+  bool starting_;
+  // Controls whether the child process should be terminated on browser
+  // shutdown. Default behavior is to terminate the child.

[rvargas (doing something else), 2015/03/27 22:01:22]

nit: There is no default behavior anymore.

Note however that there is an specific exception that allows default arguments
for constructors, so we could have a default behavior.

[no sievers, 2015/03/27 23:13:37]

Good idea. Made it a default argument. (Unfortunately all call sites except for
the renderer go through BrowserChildProcessHost::Launch() and still need to be
adapted.)

+  const bool terminate_child_on_shutdown_;
+
+  base::WeakPtrFactory<ChildProcessLauncher> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildProcessLauncher);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_CHILD_PROCESS_LAUNCHER_H_