Provide gtest printers for ui/gfx geometry types

ui/gfx/geometry/vector3d_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.
 
 // Defines a simple float vector class.  This class is used to indicate a
 // distance in two dimensions between two points. Subtracting two points should
 // produce a vector, and adding a vector to a point produces the point at the
 // vector's distance from the original point.
 
 #ifndef UI_GFX_GEOMETRY_VECTOR3D_F_H_
 #define UI_GFX_GEOMETRY_VECTOR3D_F_H_
 
+#include <iosfwd>
 #include <string>
 
 #include "ui/gfx/geometry/vector2d_f.h"
 #include "ui/gfx/gfx_export.h"
 
 namespace gfx {
 
 class GFX_EXPORT Vector3dF {
  public:
   Vector3dF();
@@ skipping 89 matching lines @@
 GFX_EXPORT Vector3dF ScaleVector3d(const Vector3dF& v,
                                    float x_scale,
                                    float y_scale,
                                    float z_scale);
 
 // Return a vector that is |v| scaled by the given scale factor.
 inline Vector3dF ScaleVector3d(const Vector3dF& v, float scale) {
   return ScaleVector3d(v, 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 Vector3dF& vector, ::std::ostream* os);
+
 }  // namespace gfx
 
 #endif // UI_GFX_GEOMETRY_VECTOR3D_F_H_