Have each SandboxedProcessLauncherDelegate maintain a zygote.

content/browser/zygote_host/zygote_host_impl_linux.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_ZYGOTE_HOST_ZYGOTE_HOST_IMPL_LINUX_H_
 #define CONTENT_BROWSER_ZYGOTE_HOST_ZYGOTE_HOST_IMPL_LINUX_H_
 
-#include <stddef.h>
-
+#include <map>

[mdempsky, 2016/01/05 22:41:57]

No need for <map> here.

Oh, you should add <sys/types.h> for pid_t and "base/process/process_handle.h"
for base::ProcessHandle though.

[Greg K, 2016/01/06 18:20:41]

Done.

 #include <set>
 #include <string>
-#include <vector>
 
-#include "base/pickle.h"
-#include "base/process/kill.h"
 #include "base/synchronization/lock.h"
-#include "content/public/browser/file_descriptor_info.h"
 #include "content/public/browser/zygote_host_linux.h"
 
 namespace base {
 template<typename Type>
 struct DefaultSingletonTraits;
 }  // namespace base
 
 namespace content {
 
 class CONTENT_EXPORT ZygoteHostImpl : public ZygoteHost {
  public:
   // Returns the singleton instance.
   static ZygoteHostImpl* GetInstance();
 
   void Init(const std::string& sandbox_cmd);
 
-  // After the last known Zygote child exits, notify the Zygote to exit.
-  void TearDownAfterLastChild();
+  // Retrieves the sandbox command passed into Init();
+  const std::string& SandboxCommand() const;
 
-  // Tries to start a process of type indicated by process_type.
-  // Returns its pid on success, otherwise
-  // base::kNullProcessHandle;
-  pid_t ForkRequest(const std::vector<std::string>& command_line,
-                    scoped_ptr<FileDescriptorInfo> mapping,
-                    const std::string& process_type);
-  void EnsureProcessTerminated(pid_t process);
+  // Tells the ZygoteHost the PIDs of all the zygotes.
+  void AddZygotePid(pid_t pid);
 
-  // Get the termination status (and, optionally, the exit code) of
-  // the process. |exit_code| is set to the exit code of the child
-  // process. (|exit_code| may be NULL.)
-  // Unfortunately the Zygote can not accurately figure out if a process
-  // is already dead without waiting synchronously for it.
-  // |known_dead| should be set to true when we already know that the process
-  // is dead. When |known_dead| is false, processes could be seen as
-  // still running, even when they're not. When |known_dead| is true, the
-  // process will be SIGKILL-ed first (which should have no effect if it was
-  // really dead). This is to prevent a waiting waitpid() from blocking in
-  // a single-threaded Zygote. See crbug.com/157458.
-  base::TerminationStatus GetTerminationStatus(base::ProcessHandle handle,
-                                               bool known_dead,
-                                               int* exit_code);
+  // Returns whether or not this pid is the pid of a zygote.
+  bool IsZygotePid(pid_t pid) override;
 
-  // ZygoteHost implementation:
-  pid_t GetPid() const override;
-  int GetSandboxStatus() const override;
+  void SetRendererSandboxStatus(int status);
+  int GetRendererSandboxStatus() const override;
   void AdjustRendererOOMScore(base::ProcessHandle process_handle,
                               int score) override;
 
  private:
   friend struct base::DefaultSingletonTraits<ZygoteHostImpl>;
 
   ZygoteHostImpl();
   ~ZygoteHostImpl() override;
 
-  // Notify the Zygote to exit immediately. This object should not be
-  // used afterwards.
-  void TearDown();
-
-  // Should be called every time a Zygote child is born.
-  void ZygoteChildBorn(pid_t process);
-
-  // Should be called every time a Zygote child died.
-  void ZygoteChildDied(pid_t process);
-
-  // Sends |data| to the zygote via |control_fd_|.  If |fds| is non-NULL, the
-  // included file descriptors will also be passed.  The caller is responsible
-  // for acquiring |control_lock_|.
-  bool SendMessage(const base::Pickle& data, const std::vector<int>* fds);
-
-  ssize_t ReadReply(void* buf, size_t buflen);
-
-  // Whether we should use the namespace sandbox instead of the setuid sandbox.
-  bool ShouldUseNamespaceSandbox();
-
-  int control_fd_;  // the socket to the zygote
-  // A lock protecting all communication with the zygote. This lock must be
-  // acquired before sending a command and released after the result has been
-  // received.
-  base::Lock control_lock_;
-  pid_t pid_;
-  bool init_;
+  int renderer_sandbox_status_;
   bool use_suid_sandbox_for_adj_oom_score_;
   std::string sandbox_binary_;
-  bool have_read_sandbox_status_word_;
-  int sandbox_status_;
-  // A lock protecting list_of_running_zygote_children_ and
-  // should_teardown_after_last_child_exits_.
-  base::Lock child_tracking_lock_;
-  std::set<pid_t> list_of_running_zygote_children_;
-  bool should_teardown_after_last_child_exits_;
+  // This lock protects the |zygote_pids_| set.
+  base::Lock zygote_pids_lock_;
+  // This is a set of PIDs representing all the running zygotes.
+  std::set<pid_t> zygote_pids_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ZYGOTE_HOST_ZYGOTE_HOST_IMPL_LINUX_H_