Replace base::Timer with behavior-specific timers in tools/

This CL replaces base::Timer with its subclasses.
As base::Timer changes its behavior subject to its construction time
flags, that makes hard to see the actual timer behavior, especially
it's unclear when a timer is injected from other components.
Also, that OnceCallback support of base::Timer is hard to implement on
the dynamically determined invocation pattern.

Bug: 850247
Change-Id: I38b7d932304466a9d86bbd577f9918149914f8ea
Reviewed-on: https://chromium-review.googlesource.com/1128694Reviewed-by: Martin Barbella <mbarbella@chromium.org>
Commit-Queue: Taiju Tsuiki <tzik@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573522}

tools/ipc_fuzzer/message_replay/replay_process.cc

@@ -180,10 +180,9 @@ void ReplayProcess::SendNextMessage() {
 }
 
 void ReplayProcess::Run() {
-  timer_.reset(new base::Timer(false, true));
-  timer_->Start(FROM_HERE,
-                base::TimeDelta::FromMilliseconds(1),
-                base::Bind(&ReplayProcess::SendNextMessage,
+  base::RepeatingTimer timer;
+  timer.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(1),
+              base::BindRepeating(&ReplayProcess::SendNextMessage,
                                   base::Unretained(this)));
   base::RunLoop().Run();
 }

tools/ipc_fuzzer/message_replay/replay_process.h

@@ -66,7 +66,6 @@ class ReplayProcess : public IPC::Listener {
   base::MessageLoop main_loop_;
   base::Thread io_thread_;
   base::WaitableEvent shutdown_event_;
-  std::unique_ptr<base::Timer> timer_;
   MessageVector messages_;
   size_t message_index_;