Add unittests target to the binary distribution (issue #1632)

- Move all tests from the top-level directory to tests/.
- Move files shared by cefclient and unittests to tests/shared/.
- Add a fused (single header/source file) version of gtest in
  tests/gtest/ with associated CMake configuration.
- Test-only headers are now exposed in include/test/. Unit test
  targets must define UNIT_TEST in order to access them.
- Replace usage of USING_CEF_SHARED with WRAPPING_CEF_SHARED for
  clarity (only the libcef_dll_wrapper target should define it).
- Remove the RENAME_DIRECTORY CMake macro which is no longer used.
- Remove C++11 usage from unittests sources for compatibility with
  the binary distribution configuration.
- Windows: Fix build errors due to chrome_elf.dll and imm32.lib
  missing from the CMake configuration.

tests/shared/common/client_app_other.h

@@ -0,0 +1,25 @@
+// Copyright (c) 2015 The Chromium Embedded Framework Authors. All rights
+// reserved. Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+
+#ifndef CEF_TESTS_SHARED_COMMON_CLIENT_APP_OTHER_H_
+#define CEF_TESTS_SHARED_COMMON_CLIENT_APP_OTHER_H_
+#pragma once
+
+#include "tests/shared/common/client_app.h"
+
+namespace client {
+
+// Client app implementation for other process types.
+class ClientAppOther : public ClientApp {
+ public:
+  ClientAppOther();
+
+ private:
+  IMPLEMENT_REFCOUNTING(ClientAppOther);
+  DISALLOW_COPY_AND_ASSIGN(ClientAppOther);
+};
+
+}  // namespace client
+
+#endif  // CEF_TESTS_SHARED_COMMON_CLIENT_APP_OTHER_H_