Provide gtest printers for ui/gfx geometry types

ui/gfx/geometry/size_f.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_F_H_
 #define UI_GFX_GEOMETRY_SIZE_F_H_
 
+#include <iosfwd>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "ui/gfx/geometry/size_base.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 // A floating version of gfx::Size.
 class GFX_EXPORT SizeF : public SizeBase<SizeF, float> {
@@ skipping 24 matching lines @@
 GFX_EXPORT SizeF ScaleSize(const SizeF& p, float x_scale, float y_scale);
 
 inline SizeF ScaleSize(const SizeF& p, float scale) {
   return ScaleSize(p, scale, scale);
 }
 
 #if !defined(COMPILER_MSVC)
 extern template class SizeBase<SizeF, float>;
 #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 SizeF& size, ::std::ostream* os);
+
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_SIZE_F_H_