Remove use of deprecated MessageLoop methods in remoting.

MessageLoop::PostTask/PostDelayedTask/DeleteSoon/ReleaseSoon
are deprecated. This CL makes the following replacements to
remove some uses of these methods:

"MessageLoop(ForUI|ForIO)::current()->PostTask" ->
  "ThreadTaskRunnerHandle::Get()->PostTask"
"MessageLoop(ForUI|ForIO)::current()->PostDelayedTask" ->
  "ThreadTaskRunnerHandle::Get()->PostDelayedTask"
"MessageLoop(ForUI|ForIO)::current()->DeleteSoon" ->
  "ThreadTaskRunnerHandle::Get()->DeleteSoon"
"MessageLoop(ForUI|ForIO)::current()->ReleaseSoon" ->
  "ThreadTaskRunnerHandle::Get()->ReleaseSoon"

In files where these replacements are made, it adds these includes:
  #include "base/location.h"
  #include "base/single_thread_task_runner.h"
  #include "base/threading/thread_task_runner_handle.h"

And removes this include if it is no longer required:
  #include "base/message_loop/message_loop.h"

Why ThreadTaskRunnerHandle::Get() instead of
MessageLoop::current()->task_runner()?
 - The two are equivalent on threads that run a MessageLoop.
 - MessageLoop::current() doesn't work in base/task_scheduler
   because the scheduler's thread don't run MessageLoops.
   This CL will therefore facilitate the migration of browser
   threads to base/task_scheduler.

Steps to generate this patch:
1. Run message_loop_cleanup.py (see code on the bug).
2. Run tools/sort-headers.py on modified files.
3. Run git cl format.

BUG=616447
R=garykac@chromium.org

Review-Url: https://codereview.chromium.org/2031083002
Cr-Commit-Position: refs/heads/master@{#398062}

remoting/protocol/channel_multiplexer_unittest.cc

@@ -7,8 +7,11 @@
 #include <utility>
 
 #include "base/bind.h"
+#include "base/location.h"
 #include "base/message_loop/message_loop.h"
 #include "base/run_loop.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "net/base/net_errors.h"
 #include "net/socket/socket.h"
 #include "net/socket/stream_socket.h"
@@ -36,7 +39,7 @@ const char kTestChannelName2[] = "test2";
 
 
 void QuitCurrentThread() {
-  base::MessageLoop::current()->PostTask(
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE, base::MessageLoop::QuitWhenIdleClosure());
 }
 

remoting/protocol/pseudotcp_adapter_unittest.cc

@@ -9,7 +9,10 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/compiler_specific.h"
+#include "base/location.h"
 #include "base/memory/ptr_util.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "jingle/glue/thread_wrapper.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
@@ -127,7 +130,7 @@ class FakeSocket : public P2PDatagramSocket {
            const net::CompletionCallback& callback) override {
     DCHECK(buf);
     if (peer_socket_) {
-      base::MessageLoop::current()->PostDelayedTask(
+      base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
           FROM_HERE,
           base::Bind(&FakeSocket::AppendInputPacket,
                      base::Unretained(peer_socket_),

remoting/test/fake_network_manager.cc

@@ -5,8 +5,10 @@
 #include "remoting/test/fake_network_manager.h"
 
 #include "base/bind.h"
+#include "base/location.h"
 #include "base/logging.h"
-#include "base/message_loop/message_loop.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "jingle/glue/utils.h"
 #include "third_party/webrtc/base/socketaddress.h"
 
@@ -24,10 +26,9 @@ FakeNetworkManager::~FakeNetworkManager() {
 
 void FakeNetworkManager::StartUpdating() {
   started_ = true;
-  base::MessageLoop::current()->PostTask(
-      FROM_HERE,
-      base::Bind(&FakeNetworkManager::SendNetworksChangedSignal,
-                 weak_factory_.GetWeakPtr()));
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(&FakeNetworkManager::SendNetworksChangedSignal,
+                            weak_factory_.GetWeakPtr()));
 }
 
 void FakeNetworkManager::StopUpdating() {