Singleton must be created on request

The creation of singleton relies on the `userData` dir, which can be
changed by user, we have to ensure singleton uses the `userData` dir set
by user.

chromium_src/chrome/browser/process_singleton.h

@@ -62,7 +62,8 @@ class ProcessSingleton {
       base::Callback<bool(const base::CommandLine::StringVector& command_line,
                           const base::FilePath& current_directory)>;
 
-  explicit ProcessSingleton(const base::FilePath& user_data_dir);
+  ProcessSingleton(const base::FilePath& user_data_dir,
+                   const NotificationCallback& notification_callback);
   ~ProcessSingleton();
 
   // Notify another process, if available. Otherwise sets ourselves as the
@@ -98,11 +99,6 @@ class ProcessSingleton {
       const ShouldKillRemoteProcessCallback& display_dialog_callback);
 #endif
 
-  void RegisterSingletonNotificationCallback(
-      const NotificationCallback& callback) {
-    notification_callback_ = callback;
-  }
-
  protected:
   // Notify another process, if available.
   // Returns true if another process was found and notified, false if we should

chromium_src/chrome/browser/process_singleton_posix.cc

@@ -85,6 +85,7 @@
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/platform_thread.h"
+#include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
@@ -716,9 +717,13 @@ void ProcessSingleton::LinuxWatcher::SocketReader::FinishWithACK(
 ///////////////////////////////////////////////////////////////////////////////
 // ProcessSingleton
 //
-ProcessSingleton::ProcessSingleton(const base::FilePath& user_data_dir)
-    : current_pid_(base::GetCurrentProcId()) {
+ProcessSingleton::ProcessSingleton(
+    const base::FilePath& user_data_dir,
+    const NotificationCallback& notification_callback)
+    : notification_callback_(notification_callback),
+      current_pid_(base::GetCurrentProcId()) {
   // The user_data_dir may have not been created yet.
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   base::CreateDirectoryAndGetError(user_data_dir, nullptr);
 
   socket_path_ = user_data_dir.Append(kSingletonSocketFilename);
@@ -957,6 +962,7 @@ void ProcessSingleton::DisablePromptForTesting() {
 }
 
 bool ProcessSingleton::Create() {
+  base::ThreadRestrictions::ScopedAllowIO allow_io;
   int sock;
   sockaddr_un addr;
 

chromium_src/chrome/browser/process_singleton_win.cc

@@ -182,8 +182,11 @@ bool TerminateAppWithError() {
 
 }  // namespace
 
-ProcessSingleton::ProcessSingleton(const base::FilePath& user_data_dir)
-    : is_virtualized_(false),
+ProcessSingleton::ProcessSingleton(
+    const base::FilePath& user_data_dir,
+    const NotificationCallback& notification_callback)
+    : notification_callback_(notification_callback),
+      is_virtualized_(false),
       lock_file_(INVALID_HANDLE_VALUE),
       user_data_dir_(user_data_dir),
       should_kill_remote_process_callback_(base::Bind(&TerminateAppWithError)) {