Revert of 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 <sys/types.h>
+#include <stddef.h>
 
 #include <set>
 #include <string>
+#include <vector>
 
-#include "base/process/process_handle.h"
+#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);
 
-  // Retrieves the sandbox command passed into Init();
-  const std::string& SandboxCommand() const;
+  // After the last known Zygote child exits, notify the Zygote to exit.
+  void TearDownAfterLastChild();
 
-  // Tells the ZygoteHost the PIDs of all the zygotes.
-  void AddZygotePid(pid_t pid);
+  // 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);
 
-  // Returns whether or not this pid is the pid of a zygote.
-  bool IsZygotePid(pid_t pid) override;
+  // 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);
 
-  void SetRendererSandboxStatus(int status);
-  int GetRendererSandboxStatus() const override;
+  // ZygoteHost implementation:
+  pid_t GetPid() const override;
+  int GetSandboxStatus() const override;
   void AdjustRendererOOMScore(base::ProcessHandle process_handle,
                               int score) override;
 
  private:
   friend struct base::DefaultSingletonTraits<ZygoteHostImpl>;
 
   ZygoteHostImpl();
   ~ZygoteHostImpl() override;
 
-  int renderer_sandbox_status_;
+  // 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_;
   bool use_suid_sandbox_for_adj_oom_score_;
   std::string sandbox_binary_;
-  // 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_;
+  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_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ZYGOTE_HOST_ZYGOTE_HOST_IMPL_LINUX_H_