Provide gtest printers for ui/gfx geometry types

ui/gfx/geometry/size_f.h

Index: ui/gfx/geometry/size_f.h
diff --git a/ui/gfx/geometry/size_f.h b/ui/gfx/geometry/size_f.h
index 8ec5628e62d1203f2ee93d4557b7c043c29138e1..5763d197f48d3c96cc5e346cb701ebd13b80d7fc 100644
--- a/ui/gfx/geometry/size_f.h
+++ b/ui/gfx/geometry/size_f.h
@@ -5,6 +5,7 @@
 #ifndef UI_GFX_GEOMETRY_SIZE_F_H_
 #define UI_GFX_GEOMETRY_SIZE_F_H_
 
+#include <iosfwd>
 #include <string>
 
 #include "base/compiler_specific.h"
@@ -49,6 +50,11 @@ inline SizeF ScaleSize(const SizeF& p, float scale) {
 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_