Remove MessageLoop::current()->RunUntilIdle() in net.

This CL replaces MessageLoop::current()->RunUntilIdle() with
RunLoop().RunUntilIdle() in net.

In files where this replacement is made, it adds this include:
  #include "base/run_loop.h"
And removes this include if it is no longer required:
  #include "base/message_loop/message_loop.h"

Why?
- The fact that there's a MessageLoop on the thread is an
  unnecessary implementation detail. When browser threads
  are migrated to base/task_scheduler, tasks will no longer
  have access to a MessageLoop but they will be able to use
  RunLoop.
- MessageLoop::RunUntilIdle() is deprecated.

Steps to generate this patch:
1. Run message_loop_cleanup_3.py (see code on the bug).
2. Run tools/sort-headers.py on modified files.
3. Run git cl format.

BUG=616447
[email protected]

Review-Url: https://codereview.chromium.org/2053133002
Cr-Commit-Position: refs/heads/master@{#399197}
diff --git a/net/quic/quic_network_transaction_unittest.cc b/net/quic/quic_network_transaction_unittest.cc
index 6c3fdfd..710584c4 100644
--- a/net/quic/quic_network_transaction_unittest.cc
+++ b/net/quic/quic_network_transaction_unittest.cc
@@ -274,16 +274,16 @@
 
   void SetUp() override {
     NetworkChangeNotifier::NotifyObserversOfIPAddressChangeForTests();
-    base::MessageLoop::current()->RunUntilIdle();
+    base::RunLoop().RunUntilIdle();
   }
 
   void TearDown() override {
     NetworkChangeNotifier::NotifyObserversOfIPAddressChangeForTests();
     // Empty the current queue.
-    base::MessageLoop::current()->RunUntilIdle();
+    base::RunLoop().RunUntilIdle();
     PlatformTest::TearDown();
     NetworkChangeNotifier::NotifyObserversOfIPAddressChangeForTests();
-    base::MessageLoop::current()->RunUntilIdle();
+    base::RunLoop().RunUntilIdle();
   }
 
   std::unique_ptr<QuicEncryptedPacket> ConstructClientConnectionClosePacket(
@@ -2162,7 +2162,7 @@
 
   void SetUp() override {
     NetworkChangeNotifier::NotifyObserversOfIPAddressChangeForTests();
-    base::MessageLoop::current()->RunUntilIdle();
+    base::RunLoop().RunUntilIdle();
 
     HttpNetworkSession::Params params;
 
@@ -2201,10 +2201,10 @@
   void TearDown() override {
     NetworkChangeNotifier::NotifyObserversOfIPAddressChangeForTests();
     // Empty the current queue.
-    base::MessageLoop::current()->RunUntilIdle();
+    base::RunLoop().RunUntilIdle();
     PlatformTest::TearDown();
     NetworkChangeNotifier::NotifyObserversOfIPAddressChangeForTests();
-    base::MessageLoop::current()->RunUntilIdle();
+    base::RunLoop().RunUntilIdle();
   }
 
   void SetAlternativeService(const std::string& origin) {