Remove calls to deprecated MessageLoop methods on Windows and Linux.

net/tools/get_server_time/get_server_time.cc

Index: net/tools/get_server_time/get_server_time.cc
diff --git a/net/tools/get_server_time/get_server_time.cc b/net/tools/get_server_time/get_server_time.cc
index 6bb3471d1626c38edc98dee082f10376b59fb614..ec30690f020e6cc3ee48c6d55bfc49ddd8e767c8 100644
--- a/net/tools/get_server_time/get_server_time.cc
+++ b/net/tools/get_server_time/get_server_time.cc
@@ -25,6 +25,7 @@
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
@@ -252,7 +253,7 @@ int main(int argc, char* argv[]) {
       start_ticks.ToInternalValue());
 
   // |delegate| quits |main_loop| when the request is done.
-  main_loop.Run();
+  base::RunLoop().Run();

[agl, 2016/08/06 00:44:00]

The |main_loop| variable is still created and passed to
TrivialURLRequestContextGetter, but now never run?

[fdoray, 2016/08/06 01:26:14]

MessageLoop(ForIO|ForUI) sets a pointer to itself in TLS when it is
instantiated. This pointer can be retrieved by calling MessageLoop::current().
RunLoop().Run() runs the MessageLoop returned by MessageLoop::current().
Therefore, |main_loop| is still important.

Why do we ask people to use RunLoop / why are we deprecating MessageLoop::Run?
- Our long-term goal is to deprecate MessageLoop::Quit/QuitWhenIdle. With these
methods, it isn't clear which call to Run() is exited. It is clearer with
RunLoop. E.g.:

void FunctionA() {
  ...
  if (...) {
     MessageLoop::current()->Quit();
     // What? Did I just killed the thread? Or a nested run of the MessageLoop?
  }
}

void FunctionB() {
  ThreadTaskRunnerHandle::Get()->PostTask(
    FROM_HERE, Bind(&FunctionA));
  MessageLoop::current()->Run();
}

vs.

void FunctionA(RunLoop* run_loop) {
  ...
  if (...) {
     run_loop->Quit();
  }
}

void FunctionB() {
  RunLoop run_loop;
  ThreadTaskRunnerHandle::Get()->PostTask(
    FROM_HERE, Bind(&FunctionA, Unretained(&run_loop)));
  run_loop.Run();
}

- Many browser threads that are currently backed by a MessageLoop are about to
be replaced with base/task_scheduler. RunLoop().Run() will work with
base/task_scheduler (will run nested tasks), but MessageLoop::current()->Run()
won't.

Please note that changes to this code don't affect its behavior. See
https://cs.chromium.org/chromium/src/base/message_loop/message_loop.cc?sq=pac...

 
   const base::Time end_time = base::Time::Now();
   const base::TimeTicks end_ticks = base::TimeTicks::Now();