Provide gtest printers for ui/gfx geometry types

ui/gfx/geometry/quad_f.h

Index: ui/gfx/geometry/quad_f.h
diff --git a/ui/gfx/geometry/quad_f.h b/ui/gfx/geometry/quad_f.h
index 25f8b2b34b36867f5d1d92d35fff18c004aa417a..ada5c54cae3fdb521db8e50f52c49eb408892b9d 100644
--- a/ui/gfx/geometry/quad_f.h
+++ b/ui/gfx/geometry/quad_f.h
@@ -7,6 +7,7 @@
 
 #include <algorithm>
 #include <cmath>
+#include <iosfwd>
 #include <string>
 
 #include "ui/gfx/geometry/point_f.h"
@@ -104,6 +105,11 @@ GFX_EXPORT QuadF operator+(const QuadF& lhs, const Vector2dF& rhs);
 // inverse of the vector.
 GFX_EXPORT QuadF operator-(const QuadF& lhs, const Vector2dF& rhs);
 
+// 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 QuadF& quad, ::std::ostream* os);
+
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_QUAD_F_H_