cc: When the transform's scale is unknown, draw render surfaces at the resolution of the screen.

cc/math_util.cc

 // Copyright 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.
 
 #include "cc/math_util.h"
 
 #include <cmath>
 #include <limits>
 
 #include "ui/gfx/quad_f.h"
@@ skipping 365 matching lines @@
     transform.matrix().setDouble(2, 2, 1);
     transform.matrix().setDouble(3, 2, 0);
     transform.matrix().setDouble(2, 3, 0);
 }
 
 static inline float scaleOnAxis(double a, double b, double c)
 {
     return std::sqrt(a * a + b * b + c * c);
 }
 
-gfx::Vector2dF MathUtil::computeTransform2dScaleComponents(const gfx::Transform& transform)
+gfx::Vector2dF MathUtil::computeTransform2dScaleComponents(const gfx::Transform& transform, float fallbackValue)
 {
     if (transform.HasPerspective())
-        return gfx::Vector2dF(1, 1);
+        return gfx::Vector2dF(fallbackValue, fallbackValue);
     float xScale = scaleOnAxis(transform.matrix().getDouble(0, 0), transform.matrix().getDouble(1, 0), transform.matrix().getDouble(2, 0));
     float yScale = scaleOnAxis(transform.matrix().getDouble(0, 1), transform.matrix().getDouble(1, 1), transform.matrix().getDouble(2, 1));
     return gfx::Vector2dF(xScale, yScale);
 }
 
 float MathUtil::smallestAngleBetweenVectors(gfx::Vector2dF v1, gfx::Vector2dF v2)
 {
     double dotProduct = gfx::DotProduct(v1, v2) / v1.Length() / v2.Length();
     // Clamp to compensate for rounding errors.
     dotProduct = std::max(-1.0, std::min(1.0, dotProduct));
@@ skipping 94 matching lines @@
     matrix.setDouble(1, 0, b);
     matrix.setDouble(0, 1, c);
     matrix.setDouble(1, 1, d);
     matrix.setDouble(0, 3, e);
     matrix.setDouble(1, 3, f);
 
     return result;
 }
 
 }  // namespace cc