[Chromoting] Use HostExperimentSessionPlugin in host

remoting/host/host_session_options_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "remoting/host/host_session_options.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace remoting {
-namespace protocol {
 
 TEST(HostSessionOptionsTest, ShouldBeAbleToAppendOptions) {
   HostSessionOptions options;
   options.Import("A:, B C :1, DE:2, EF");
   ASSERT_TRUE(options.Get("A"));
   ASSERT_EQ(*options.Get("B C "), "1");
   ASSERT_EQ(*options.Get("DE"), "2");
   ASSERT_FALSE(options.Get("EF"));
   ASSERT_FALSE(options.Get(" EF"));
   ASSERT_FALSE(options.Get("--FF"));
@@ skipping 24 matching lines @@
   HostSessionOptions options;
   options.Import("A:,B:,C:D,E:V");
   std::string result = options.Export();
 
   HostSessionOptions other;
   other.Append("C", "X");
   other.Import(result);
   ASSERT_EQ(options.Export(), other.Export());
 }
 
-}  // namespace protocol
 }  // namespace remoting