Use a direct include of strings headers in remoting/.

remoting/base/capabilities_unittest.cc

 // Copyright 2013 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 <algorithm>
 #include <vector>
 
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "remoting/base/capabilities.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
 
 struct HasCapabilityTestData {
   const char* capabilities;
   const char* key;
   bool result;
 };
@@ skipping 78 matching lines @@
     Tokenize(data[i].left, " ", &caps);
 
     do {
       EXPECT_EQ(IntersectCapabilities(JoinString(caps, " "), data[i].right),
                 data[i].result);
     } while (std::next_permutation(caps.begin(), caps.end()));
   }
 }
 
 }  // namespace remoting