Provide gtest printers for ui/gfx geometry types

ui/gfx/geometry/point3_f.h

Index: ui/gfx/geometry/point3_f.h
diff --git a/ui/gfx/geometry/point3_f.h b/ui/gfx/geometry/point3_f.h
index 45bae6e8d328638da2c3bfac693f5855110bbf28..262e3555d31849f0e41b6a4569fddde8f1e6880c 100644
--- a/ui/gfx/geometry/point3_f.h
+++ b/ui/gfx/geometry/point3_f.h
@@ -5,6 +5,7 @@
 #ifndef UI_GFX_GEOMETRY_POINT3_F_H_
 #define UI_GFX_GEOMETRY_POINT3_F_H_
 
+#include <iosfwd>
 #include <string>
 
 #include "ui/gfx/geometry/point_f.h"
@@ -115,6 +116,11 @@ inline Point3F ScalePoint(const Point3F& p, float scale) {
   return ScalePoint(p, scale, scale, scale);
 }
 
+// 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 Point3F& point, ::std::ostream* os);
+
 }  // namespace gfx
 
 #endif  // UI_GFX_GEOMETRY_POINT3_F_H_