Use a direct include of strings headers in chrome/common/, part 1.

chrome/common/extensions/api/commands/commands_manifest_unittest.cc

 // Copyright (c) 2012 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 "chrome/common/extensions/manifest_tests/extension_manifest_test.h"
 
 #include "base/command_line.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/api/commands/commands_handler.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace errors = extension_manifest_errors;
 
 namespace extensions {
 
 class CommandsManifestTest : public ExtensionManifestTest {
 };
@@ skipping 67 matching lines @@
       LoadAndExpectSuccess("browser_action_synthesizes_command.json");
   // An extension with a browser action but no extension command specified
   // should get a command assigned to it.
   const extensions::Command* command =
       CommandsInfo::GetBrowserActionCommand(extension.get());
   ASSERT_TRUE(command != NULL);
   ASSERT_EQ(ui::VKEY_UNKNOWN, command->accelerator().key_code());
 }
 
 }  // namespace extensions