Provide gtest printers for ui/gfx geometry types

ui/gfx/geometry/size.h

 // 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.
 
 #ifndef UI_GFX_GEOMETRY_SIZE_H_
 #define UI_GFX_GEOMETRY_SIZE_H_
 
+#include <iosfwd>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "ui/gfx/geometry/size_base.h"
 #include "ui/gfx/geometry/size_f.h"
 #include "ui/gfx/gfx_export.h"
 
 #if defined(OS_WIN)
 typedef struct tagSIZE SIZE;
 #elif defined(OS_IOS)
@@ skipping 37 matching lines @@
 }
 
 inline bool operator!=(const Size& lhs, const Size& rhs) {
   return !(lhs == rhs);
 }
 
 #if !defined(COMPILER_MSVC)
 extern template class SizeBase<Size, int>;
 #endif
 
+// This is declared here for use in gtest-based unit tests but is defined in
+// the gfx_test_support target. Depend on that to use this in your unit test.
+// This should not be used in production code - call ToString() instead.
+void PrintTo(const Size& size, ::std::ostream* os);
+
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_SIZE_H_